In this study， an improved periodic graph method was proposed for wave power spectrum analysis， optimizing the computational process of spectrum estimation and enhancing the inversion speed of parameters such as wave height and wave period. An algorithm for estimating wave direction was investigated. The surface slope was derived from the heights of three points on the wave surface measured by the radar array， and the wave direction information was determined through the interrelationship between the slope and the heave motion of the water surface， simplifying the computational approach for wave direction inversion. Experimental results of comparison with buoy data demonstrate that the correlation of wave parameters obtained by the inversion method presented in this paper and the Datawell Mk III wave buoy reaches 98.4%， suiting real-world applications.