Abstract: Base on the in-situ measurements in soft rocks influence of the wall subsiding on roadwayfloor heave is explained. A fact is revealed that the floor of roadway is subsided under the presure ofthe roadway wall during delivering pressur from the roof. The crack and heave of the roadway floor occurred when the deformation of the floor became great. A principle of floor heave controlling is controlling is pro-Posed, which has been verified in Maoming Mine. Formulae for evaluating rodway floor heave are de-rived and gave satisfactory results in calculation.