Currently, the continuous rotary north-finder is widely discussed for its outstanding performance. However, few researches on the influence of turntable error to the continuous rotary north-finding algorithm can be found. Turntable errors, such as the stability of rotate speed, the periodic angle measurement error and the discrete angle measurement error, are studied for the north-finder based on rate biased RLG (ring laser gyro). Two north-finding algorithms are designed, which can restrain the influence of angle measurement errors and the stability of rotate speed separately. Finally, simulation and experiments are performed to verify the algorithms.