Several studies have evaluated the risk factors influencing biochemical recurrence (BCR) of prostate cancer in patients receiving salvage radiotherapy (SRT) for BCR after radical prostatectomy (RP), but the results remain conflicting. In this study, we performed a meta?analysis to resolve this conflict. We searched the following databases: PubMed, Embase, and Web of Science using the following terms in “All fields”: “salvage radiation therapy,” “salvage IMRT,” “S?IMRT,” “salvage radiotherapy,” “SRT,” “radical prostatectomy,” “RP,” “biochemical recurrence,” “BCR,” “biochemical relapse.” Eleven studies, with a total of 1383 patients, were included in our meta?analysis. Of all the variables, only Gleason score (GS) ≥7 (odds ratio [OR]: 3.82; 95% confidence interval [CI]: 2.60–5.64) and pathological tumor (pT) stage ≥3a (OR: 1.82; 95% CI: 1.36–2.42) were positively correlated with BCR. However, SRT combined with androgen deprivation therapy (ADT) (OR: 0.63; 95% CI: 0.44–0.90) and radiation therapy (RT) dose ≥64 Gy (OR: 0.35; 95% CI: 0.19–0.64) were negatively correlated with BCR. Perineural invasion (OR: 2.64;95% CI: 1.11–6.26), preoperative prostate?specific antigen (PSA) ≥10 ng ml?1 (OR: 1.36; 95% CI: 0.94–1.96), positive surgical margin (OR: 0.92; 95% CI: 0.7–1.19), and seminal vesicle involvement (SVI) (OR: 1.09; 95% CI: 0.83–1.43) had no effect on BCR. Our meta?analysis indicated that pT stage, GS, RT dose, and SRT combined with ADT may influence BCR, while preoperative PSA, surgical margin, perineural invasion, and SVI have only a weak effect on BCR.