The invention discloses a method for improving space resource utilization efficiency of an intersection entrance lane. The method for improving the space resource utilization efficiency of the intersection entrance lane includes that setting the left turn lane of the outermost side of the entrance lane into a reversible lane without changing the period and phase green light time, and changing functions of the reversible lane in real time so as to improve the space resource utilization efficiency of the same entrance lane of the intersection; gathering the left turn car traffic volume and straight going car traffic volume of the entrance lane in the signal period through a video detector, and changing a lane signal lamp and a direction indication signal lamp in the next period through numeric calculation and logical judgment so as to guide a vehicle to adapt to the lane conversion. The method for improving the space resource utilization efficiency of the intersection entrance lane balances the space resource utilization efficiency of different directions of lanes of the intersection, timely reduces the queuing time of the vehicle at the intersection and improves the traffic efficiency.