The invention discloses a priority valve for a hydraulic excavator. The priority valve comprises a valve body, a shuttle valve core, a steel ball, a first throttle valve core, a spring, an elastic stop collar, a second throttle valve core and a two-position valve core. Ports A1 and A2 of the priority valve are respectively connected to left and right revolution guide oil ports of the excavator; ports B1 and B2 are connected with each other and are connected to a movable arm lifting guide oil port; and a port TO is connected to an oil return port of an oil tank. When the revolution and movable arm lifting compound action is performed, the movable arm is lifted and the two-position valve core changes positions simultaneously, and part of revolved guide oil is appropriately discharged back to the oil tank so as to delay the opening and reduce the opening speed of the revolution valve core and finally fulfill the aim that the movable arm lifting is prior to the revolution. The priority valve has the advantages of simple structure, low manufacturing cost, stable performance, long service life, variable priority time, wide application and the like.