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.