A new ring laser diode gyroscope (RLDG) is reported in this paper, which combines the advantage of simple configuration of ring laser gyroscope (RLG) and lower cost of fiber optical gyroscope (FOG). The resolution of the RLDG and its relations with other parameters of RLDG are analyzed theoretically. The signal readout method is discussed. A monolithic RLDG with 40mm diameter is proposed. Its resolution can be up to 0.032 rad/s theoretically.