The Prussian three-class franchise (German: Preußisches Dreiklassenwahlrecht) was an indirect electoral system used from 1848 until 1918 in the Kingdom of Prussia and for shorter periods in other German states. Voters were grouped by district into three classes, with the total tax payments in each class equal. Those who paid the most in taxes formed the first class, followed by the next highest in the second, with those who paid the least in the third. Voters in each class separately elected one third of the electors who in turn voted for the representatives. Voting was not secret. The franchise was a form of apportionment by economic class rather than geographic area or population.

Members of the Prussian House of Representatives were elected according to the three-class electoral law, as were the city councils of Prussian cities and towns in accordance with the Prussian Municipal Code. After decades of controversy and failed attempts at reform, which for many caused the Prussian three-class franchise to become a hated symbol of Prussia's democratic shortfalls, it was finally abolished early in the German Revolution of 1918–1919 that broke out following Germany's defeat in World War I.

Even though there were considerable differences between districts in the tax levels at which the cutoffs between classes were made, the system tended to favor conservatives and rural areas over left liberals and cities. Voter turnout was also significantly lower under three-class voting than it was in elections for the German Reichstag, which did not use the system. Despite the diminished weight of many votes, the three class franchise did have the advantage of allowing all males to vote, which many contemporaneous electoral systems in other German states and European countries did not do.

The legal basis for the three-class electoral system was the "Ordinance on Conducting the Election of Deputies to the Second Chamber" of 30 May 1849 and the "Regulations on Conducting Elections to the House of Deputies", which was issued for the implementation of the 30 May ordinance and then repeatedly amended. The three-class electoral system was made part of the revised Prussian constitution of 31 January 1850 (paragraph 71).

With only one paragraph added to it before 1918, the ordinance remained fundamentally unchanged for the duration of its use. It was, however, partially invalidated several times or replaced by new regulations. In 1860 the electoral districts and polling places were set by law. In 1891 and 1893 the formation of electoral classes was reformed, and in 1906 some minor changes were introduced to streamline the electoral process.

Every Prussian male who had reached the age of 25 and had lived in a Prussian municipality for at least six months was eligible to vote. He could not have lost his civil rights through a legal judgment or be receiving public assistance for the poor. Under paragraph 49 of the Reich Military Act of 1874 (Reichs-Militärgesetz), active military personnel, with the exception of military officers, were excluded from the right to vote both in the federal states and for the Reichstag.

Those eligible to vote were divided into three classes based on the revenue from direct state taxes (class tax or classified income tax, property tax and business tax).

Within each district, the eligible voters who paid the most taxes fell into the first class. The top taxpaying eligible voters were assigned to this class until one third of the total tax revenue was reached. Then those who paid the most taxes among the remaining eligible voters were put into the second class until one-third of the total tax revenue was again reached. All remaining eligible voters – who also contributed one-third of total taxes – formed the third class.