Abstract: Through the calculation of time used in formation of magnetic chain of panzhihua titanomagnetite particles, it was gotten that the recovery of titanomagnetite by magnetic separation essentially is the recovery of magnetic chains made of titanomagnetite particles. Through the analysis of forces exerted on magnetic chain in magnetic field strength in detail, the general formula has been obtained that suits to computation of the recovery of magnetic chain made of the ferromagnetism material in magnetic separation, which has enriched the theory of magnetism reunion.