In this paper, we present a path planning algorithm for autonomous parking system. We focus on the kinematics of the car-like vehicle and improve the conventional geometric parking algorithm by proposing a new curve element named linearly steering spiral. A path planning algorithm based on smooth path searching and optimizing are presented. This method can generate smooth paths incrementally, and the reference control signals can be deduced directly once the path is determined. A simple closed-loop controller is designed in order to deal with the uncertainty from various aspects. Simulations are implemented in different scenarios including obstacle-free and cluttered environments, moreover, a real-world online experiment is executed. The results indicate that the proposed method achieves good performance on both accuracy and computational cost.