Using first-principles calculations based on density functional theory and plane pseudo-potential method, we investigate the geometric structures, magnetic properties and electronic structures of phosphorene with phosphorus substituted by carbon (CP), oxygen (OP) and sulfur (SP). The results show that the phosphorene with SP presents a less geometric distortion than with OP and CN. Although the pure phosphorene is non-magnetic, all the doped systems are magnetic, each with a magnetization value of 1 μB per cell. The doped systems with stable ferromagnetism play an important role in developing spin electric devices.