The invention discloses a catalyst adding method. The method is used in the process of preparing hydrocarbon through moving bed methanol conversion, and a fresh catalyst is added into a moving bed reactor from a catalyst tank (1). The method includes the following steps of A discharging operation, B first-time keeping operation, C charging operation and D second-time keeping operation. The steps A to D are circulated once to complete one operation circulation, and the time used for the operation circulation is called a circulation cycle. In one operation circulation, the addition amount of the fresh catalyst added into the moving bed reactor is divided by the circulation cycle to obtain the addition speed of the fresh catalyst. By adjusting the addition speed of the fresh catalyst, the addition speed of the fresh catalyst can be within the allowable error range of the addition speed, needed by the moving bed reactor, of the fresh catalyst, and the fresh catalyst is continuously supplemented to the moving bed reactor online at the addition speed, needed by the moving bed reactor, of the fresh catalyst.