A north-finding method based on orientation effect error compensation. A fiber optic gyro and an accelerometer are first arranged on a rotary table containing an angle measuring system, and then the rotary table is arranged on a carrier. The method comprises the following steps: 1) defining a geographic coordinate system, a carrier coordinate, an azimuth H, and slant angles of theta and gamma; 2) arranging the fiber optic gyro and the accelerometer on the carrier; 3) recording a current position as a position 1, successively turning the rotary table clockwise by 90DEG, recording a position 2, a position 3, and a position 4, acquiring 30s output values of the fiber optic gyro and the accelerometer on the four positions and calculating mean values, and then calculating a current pitching angle theta, a current roll angle gamma and a current coarse azimuth H1; 4) if H satisfies a relation that |H1|<=1 DEG or |H1-180 DEG|<= 1 DEG, H1 being an actual azimuth; otherwise, controlling the rotary table to turn by (90 DEG-H1) clockwise, repeating step 3), calculating a current accurate azimuth H2, and using (H1+H2) as an actual azimuth for north-finding.