Objective To evaluate the intraocular pressure (IOP)-lowering effects achieved by nonpenetrating glaucoma surgery (NPGS) in patients with open angle glaucoma. Methods Randomized controlled trials evaluating patients with primary and secondary open angle glaucoma treated with NPGS were identified and were subjected to systematic review analysis. The main outcome measurements included the percentage of IOP reduction and the complete success rate. The pooled estimates were calculated using the random effect model by comprehensive meta-analysis software version 2.0. Results Both deep sclerectomy (DS) and viscocanalostomy (VCO) were less effective than trabeculectomy (TE) in lowering IOP, with the of IOP reduction percent at 2 years being 35.2% for DS, 30.2% for VCO, and 45.6% for TE. Intraoperative use of implants and mitomycin C (MMC) improved IOP-lowering effects of DS, with IOP reduction at percent 2 years being 41.1% and 41.7%, respectively. The complete success rates at 4 years were 35.4% for DS and 22.7% for VCO, lower than that of TE (47.6%). The complete success rates of DS with implants and MMC were 64.6% and 52.1% at 4 years, respectively, both being higher than that of primary DS. NPGS caused less complications than TE. Conclusion Primary deep sclerectomy and primary viscocanalostomy can significantly lower IOP and have less complication than TE. However, the IOP-lowering effect of NPGS is slighter than primary TE. The efficacy of DS can be improved by intraoperative use of implants and MMC.