Objective：This study aims to investigate the effect of the Pseudomonas aeruginosa secreted protein Pec1 on phagocytosis of MH-S cells. Methods：The recombinant protein Pec1 was prepared by PCR amplification，plasmid construction，induced expression and protein purification. The effect of the recombinant protein Pec1 on the proliferation of MH-S cells was measured by CCK-8 kit. Neutral red was used to detect the phagocytic function of MH-S cells，and the phagocytosis of heat- inactivated Pseudomonas aeruginosa was observed by fluorescence microscope. Results：The recombinant protein Pec1 with the molecular weight of 30.5 kDa was successfully expressed and purified. Pec1 had a concentration-dependent inhibitory effect on the proliferation of MH-S cells. Pec1 decreased the endocytosis of neutral red and inhibited the phagocytosis of heat-inactivated Pseudomonas aeruginosa by MH-S cells. Conclusion：The Pseudomonas aeruginosa secreted protein Pec1 can inhibit the phagocytosis of MH-S cells.