The invention discloses a system and a method for municipal sewage treatment. The system comprises a pretreatment device, a biological treatment device, a sedimentation pool and an artificial wetland, wherein the biological reactor comprises a hypoxia reaction pool, an anaerobic reaction pool and an aerobic reaction pool which are in successive arrangement; the pretreatment device is respectively communicated with the hypoxia reaction pool and the anaerobic reaction pool; the back flow of the aerobic reaction pool is introduced to the hypoxia reaction pool; the sedimentation pool is connected with the aerobic reaction pool; the returned sludge of the sedimentation pool is introduced to the hypoxia reaction pool; the water outlet pipe of the sedimentation pool is connected with the artificial wetland; and a sludge outlet is arranged below the sedimentation pool and communicated with the sludge treatment device. Thus, a biological reactor is reasonable in biological reaction arrangement; the artificial wetland is used to treat the sewage discharged from the sedimentation pool; and plants in the artificial wetland are utilized to absorb phosphorus and nitrogen, so strong absorption effect and good denitrification and dephosphorization effects are obtained.