The invention discloses a method for actively supporting a lane side filling gob-side entry retraining. Firstly, a lane interior support and an enforcing support are built on a reserved lane according to a sounding rock condition and a working face. On the back of the working face, nogs, gangues or blockworks and the like are adopted to build a lane side filling wall along the edge of a gob. High-strength and sealed filling bags are paved on the filling wall, and high-expanding materials or cement coagulation serous fluid added with a rapid hardening early strength agent is filled into the filling bags through a grouting pump. The enforcing support is dismounted after a top plate behind the working face is movably stabilized, the high-strength and sealed filling bags are enabled to be contacted tightly with the top plate, and active support force is formed to be exerted on the top plate. By means of the active support force provided for the lane side filing wall, the top cutting capacity of a lane side filling body is enhanced, initial deflection of the entry retaining top plate is reduced, the stability of the top plate is improved, the quality of the gob-side entry retaining is improved, and repair rate of the gob-side entry retaining is reduced. The method is simple, convenient to operate and good in effect.