Chinese enterprises listed in US now face great challenges as Sarbanes-Oxley Act started to be in force on July 15, Beijing Business Journal reported.   The Act imposes new rules on those overseas enterprises with 5 million US dollars annual revenues, which increase administrative and operational complexity and difficulties, said the paper. Section 404 makes the establishment of a detailed internal control structure compulsory include environment control, risk management, corporate communication and supervision. It acts as a hurdle to enterprises entering US stock market.   The Act requires CEO and financial management unit of overseas listed companies to certify in each quarterly and annual report, among other things, that the report does not contain any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements made, in light of the circumstances under which such statements were made, not misleading, and the financial statements, and other financial information included in the report, fairly present in all material respects the financial condition and results of operations of the company. Otherwise, the responsible senior management has to bear criminal charges and up to 10 to 20 years sentence.   The strict requirements towards corporate management and auditing pose challenges towards the 46 Us-listed companies, which have invested 10 million yuan in human resources, accounting and capital management to meet up the requirements and bridge the gap of differences in expertise as well as knowledge particularly towards auditing.   Sarbanes-Oxley Act came in the wake of financial scandals in 2002. It established independent auditing control committee for listed companies, increased independence of accounting firms, strengthened the responsibilities of the release of financial statements. Section 302 and 404 require particular attention and care on the part of overseas companies preparing US listing.