The Hualong One (Chinese: 华龙一号; pinyin: Huálóng yī hào; lit. 'China Dragon №1') is a Chinese Generation III pressurized water nuclear reactor jointly developed by the China General Nuclear Power Group (CGN) and the China National Nuclear Corporation (CNNC). The CGN version, and its derived export version, is called HPR1000. It is commonly mistakenly referred to in media as the "ACPR1000" and "ACP1000", which are in fact earlier reactors design programs by CGN and CNNC.

Unit 5 of the Fuqing Nuclear Power Plant was the first Hualong One to enter commercial service on 30 January 2021.

Hualong One is jointly developed by the China National Nuclear Corporation (CNNC) and China General Nuclear Power Group (CGN), based on the three-loop ACP1000 of CNNC and ACPR1000 of CGN, which in turn are based on the French M310.

Since 2012, CNNC has been progressively merging its ACP-1000 nuclear power station design with the CGN ACPR-1000 design, while allowing some differences, under direction of the Chinese nuclear regulator. Both are three-loop designs originally based on the same French M310 design used in Daya Bay with 157 fuel assemblies, but went through different development processes (CNNC's ACP-1000 has a more domestic design with 177 fuel assemblies while CGN's ACPR-1000 is a closer copy with 157 fuel assemblies). In early 2014, it was announced that the merged design was moving from preliminary design to detailed design. Power output will be 1150 MWe, with a 60-year design life, and would use a combination of passive and active safety systems with a double containment. CNNC's 177 fuel assembly design was retained.

Initially the merged design was to be called the ACC-1000, but ultimately it was named Hualong One. In August 2014 the Chinese nuclear regulator review panel classified the design as a Generation III reactor design, with independently owned intellectual property rights. As a result of the success of the merger, ACP-1000 and ACPR-1000 designs are no longer being offered.

After the merger, both companies retain their own supply chain and their versions of the Hualong One will differ slightly (units built by CGN will retain some features from the ACPR1000) but the design is considered to be standardised. CNNC version emphasizes more passive safety due to influence from Westinghouse AP1000, with increased containment volume and two active safety trains, while CGN version has three active safety trains due to influence from Areva EPR. Some 90% of its components will be made domestically.

The Hualong One power output will be 1170 MWe gross, 1090 MWe net, with a 60-year design life, and would use a combination of passive and active safety systems with a double containment. It has a 177 assembly core design with an 18-month refuelling cycle. The power plant's utilisation rate is as high as 90%. CNNC has said its active and passive safety systems, double-layer containment and other technologies meet the highest international safety standards.

According to CNNC, the Hualong One has a construction cost of CNY17,000 per kW.