Objective To explore the role and activity mechanisms of demethylase JARID1D in the invasion and metastasis of prostate cancer in order to provide new predictive indicators and therapeutic targets for the metastasis of prostate cancer. Methods The prostate cancer cell lines 22RV1 and DU145 were transfected with lentivirus to knock down the expression of JARID1D. These cell lines were named sh-JARID1D. The change in JARID1D expression in sh-JARID1D cells was confirmed by qRT-PCR and Western Blot. Changes in cell invasion ability after decreasing JARID1D expression were detected by Transwell experiment. An experimental metastasis animal model was established by injecting sh-JARID1D cells into the tail vein of nude mice, and changes in tumor cell metastasis ability were evaluated in vivo after knockdown of JARID1D expression. The effect of JARID1D on metastasis-related gene matrix metalloproteinase 2 (MMP2) was detected by qRT-PCR and Western Blot. Results The Transwell experiment showed the increased invasion ability of prostate cancer cells after JARID1D knockdown (22RV1 cell line P< 0. 01, DU145 cell line P< 0. 001). We also found that low expression of JARID1D significantly enhanced the metastatic potential of tumor cells in nude mice (22RV1 metastasis model P< 0. 01, DU145 metastasis model P< 0. 01). Further experiments demonstrated that reducing the expression of JARID1D promoted the expression of MMP2. Conclusions Knocking down the expression of JARID1D increased the level of MMP2 in prostate cancer cells, promoting epithelial mesenchymal transition, enhancing the invasion and metastasis of prostate cancer, and thus affecting the progression of prostate cancer.