The invention provides a method and device for obtaining a wellbore storage coefficient. The method comprises the steps that bottom hole pressure and bottom hole temperature at different moments within preset time are detected, and bottom hole pressure data and bottom hole temperature data at different moments within the preset time are obtained; according to the bottom hole pressure data, the change amount of the bottom hole pressure within the preset time is obtained; according to the bottom hole pressure data and the bottom hole temperature data, the volume change amount of fluid in the shaft within the preset time is obtained; and according to the change amount of the bottom hole pressure and the volume change amount of the fluid in the shaft, the shaft storage coefficient is obtained.Therefore, a user can obtain the shaft storage coefficient through the shaft bottom pressure data and the shaft bottom temperature data which are obtained through actual measurement, and the shaft storage coefficient can better represent the actual shaft storage coefficient, and the accuracy of the shaft storage coefficient is high.