Objective: ① Observe from outside the body the photodynamic therapy of light sensitive agent CPD₅ on human pancreas cancer cells(Hs766T);② Observe the light-generated effect of Procaine on CPD₅. Method: add pancreas cancer cells with a concentration of 1×10⁵ ml into a culture panel with 96 holes,each hole 100 μl,then add in CPD₅ of different concentrations,replace the used cultures with fresh ones 24 hours later. Add Procaine to the Procaine group and physiological saline to the light-generated compare group. Expose each hole to a radiation of 670 nm laser diode with a dose of 10 J/cm² for 3 minutes. Measure the livability of cells with the dyeing cell experiment after another 24 hours of culture. Result:①The livability of pancreas cancer cells after the PDT is 2.0% when the concentration of CPD₅ is at 2.5 μg/ml. ② The light-generated effect of CPD₅ with a concentration of 2.5 μg/ml after the addition of Procaine(20 μg/ml)is the livability of pancreas cancer cells is 97.0%.Conclusion: Procaine can greatly decrease the light-generated effect of CPD₅.