A method of lane change and path planning that receives sensed signals from multiple sensors through a car computer on a vehicle to generate multiple traveling speed time-sorted information and multiple surrounding circumstance time-sorted information, and to further generate a 3×3 grid corresponding to the surroundings of the vehicle; when receiving a signal to switch on the turn signals, the car computer selects data within a time interval from those traveling speed time-sorted information and surrounding circumstance time-sorted information, respectively; and then the selected data is to be processed together with the 3×3 grid to generate a lane change space, and through a decision strategy to determine whether the lane change space complies with a safety movement strategy, and then the car computer generates a planned path of movement, such that a safest space for assisting lane change is provided for improving convenience and safety.