Abstract: The present invention discloses a method for establishing a trusted running environment in a computer. A trusted file authentication module and a trusted process memory code authentication module are preset in operation system (OS) of the computer and a secured OS is loaded and run. The trusted file authentication module intercepts all file operation behaviors, checks whether current file to be operated is a trusted file or not, and processes the file according to its operation type if it is trusted, otherwise processes the file after its eligibility is verified; the trusted process memory code authentication module authenticates on timing whether the running state and the integrality for all process code are normal or not; if any process is abnormal, giving an alarm, saving field data run by the process and closing down the process; otherwise continuing to run normally.