The allocation for the subcommittee is $50.2 billion for fiscal year 2012.
U.S. Trade Representative Ron Kirk recently said his office is "woefully short" on resources to investigate issues and had "exhausted its entire annual translation budget in three months on a single China case," the letter said.
China's laws and regulations are "much more opaque" than other members of the WTO and China's recently announced five-year plan to invest $1.5 trillion into emerging industries such as information technology could further complicate oversight, the lawmakers said.
The subcommittee markup of the bill, which hasn't been released, is July 7.
House and Senate members along with the Obama administration have expressed concerns about Chinese policies that favor domestic innovation and don't provide protections for U.S.-generated intellectual property.
In a May 10 letter to Obama administration officials during meetings with Chinese officials, House Ways and Means Republicans said the list of concerns with China "remains far too long" and include WTO inconsistent subsidies and directed lending, a lack of regulatory transparency and currency misalignment of currency.