To determine the expression and location of CPXM1 in follicular granulosa cells of laying hens and the relationship between CPXM1 expression and P₄ secretion, SWF, LWF, SYF and LYF of 5 hens were collected. Granulosa cells were scraped and the expression of CPXM1 mRNA in follicular granulosa cells at different stages of development was detected by QRT-PCR. Immunohistochemistry was used to locate the expression of CPXM1 peptide in follicles of LWF and SYF. The concentration of P₄ in follicular fluid at different stages of development were detected.As a result, the levels of CPXM1 mRNA in LWF was significantly higher than that in other follicles（P＜0.05）. The expression of CPXM1 protein was detected in theca cells, granulosa cells and cumulus cells of follicle and the expression level in LWF granulosa cell layer was significantly higher than that in other cells of LWF and cells of SYF.The concentration of P₄ in LYF follicular fluid was significantly higher than that of other follicles（P＜0.01）. In conclusion, CPXM1 may inhibit follicular development in granulosa cells.