The invention discloses a self-testing system of negative pressure loop of optical catalyzed reaction, which comprises the following parts: reacting part with magnetic stirrer, reactor, xenon lamp source, circulating part with magnetic glass piston pump, spherical glass condenser, gas-phased chromatogram, reactor, blowing vacuum extracting part with ten-shaped four-way vacuum piston, scrubbing bottle, precise vacuum pressure list and vacuum pump, sampling detecting part with gas phased chromatogram, automatic six-way sampling valve, gas-carrier bottle and gas driving bottle, temperature control part with thermostatic circulating pump, reactor temperature control jacket and spherical glass condenser. The invention can estimate the catalytic property of catalyst precisely and in time, which is fit for other optical catalyzed reacting tests in relative to gas participation or generation.