I found this helpful recap from Reuters of the cases involving China at the WTO as both a complainant ("plaintiff") and a respondent ("defendant"). You can of course visit the WTO site and plunge into the minutiae if you're so inclined, but it's easier to view this summary -
China has appealed against a World Trade Organisation ruling upholding parts of a U.S. complaint about Chinese restrictions on imports of films, books and other audio-visual material. The appeal was launched shortly after the U.S. decided to impose additional duties on imports of Chinese-made tyres, invoking for the first time a "safeguard" clause China agreed to when it joined the WTO.
China hotly protested the tyre duties and launched its own anti-dumping investigation of automotive and chicken parts imports from the U.S., whose combined value is roughly equivalent to the value of the contested tyre shipments.
At first worried that WTO entry could jeopardise Chinese jobs and businesses as foreign competitors crowded in, China is now an enthusiastic participant. It has launched several complaints to keep other markets open to the exports that drive its economy.
Since it joined the global trade body in 2001, China has brought five complaints to the WTO, and has been a defendant in 16 cases. Below are some current or recent cases at the WTO:
CASES IN WHICH CHINA IS COMPLAINANT
STEEL
China is challenging U.S. anti-dumping duties on steel products before the WTO. It is also unhappy with a series of other U.S. actions against its imports, including the safeguard duties imposed on tyres and anti-dumping duties on steel pipe used to transport oil.
China in July requested consultations on anti-dumping duties imposed by the European Union against imports of Chinese steel screws and fasteners. The EU exempted two European joint ventures that manufacture fasteners in China.
COOKED POULTRY
China launched a WTO case in April over U.S. legislation that forbids the government from beginning the process of certifying Chinese cooked poultry exporters. The House of Representatives appropriations bill extends the measure for a fourth year, while the Senate version orders the government to begin the certifying process.
CASES IN WHICH CHINA IS DEFENDANT
RAW MATERIALS
The EU and the United States argue that Chinese export restrictions, including taxes and quotas, on several raw materials unfairly elevate the international price, while keeping input prices cheaper for manufacturers in China.
DISTRIBUTION SERVICES AND INTELLECTUAL PROPERTY RIGHTS
On Aug 12, a WTO panel found in favour of a U.S. complaint that Chinese curbs on importing and distributing foreign publications and audiovisual products violated WTO commitments. China appealed on Sept. 22.
Both the U.S. and China claimed victory earlier this year when a WTO panel found that China had failed to protect and enforce intellectual property rights, but rejected the U.S. contention that China sets the threshold for prosecuting piracy so high that it is ineffective. China noted the findings did not challenge its right to censor content.
GRANTS, LOANS AND OTHER INCENTIVES
The United States, Mexico and Guatemala requested consultations regarding certain grants, loans and other incentives to encourage exports of Chinese brands.
FINANCIAL INFORMATION
China in November settled on a complaint by the EU, the United States and Canada against China's requirement that foreign financial information suppliers, including Thomson Reuters, must operate through an entity designated by the Xinhua news agency, rather than dealing directly with subscribers