We present the membership determination of the NGC 7789 open cluster located at Cassiopeia. Based on the astrometric data from Gaia Early Data Release 3 (positions, parallaxes, and proper motions) are considered to derive cluster members of the open cluster. The Hierarchical Density-Based Spatial Clustering of Applications with Noise and Gaussian Mixture Model techniques in determining the frequency and degree of a star’s membership in a cluster were being utilized in the study. We calculate the parallax and distance of the NGC 7789 cluster center to be 0.1994 ± 0.11 mas and 18637 ± 333110 pc respectively. The cluster center is calculated to be α = 359° 16' 56.44'', δ = 56° 42''38.46 ' and proper motion to be µα = −1.386 ± 0.68 mas/yr and µδ = −1.052 ± 0.37 mas/yr. We also utilized the Automated Stellar Cluster Analysis tool and obtained: log(age) = ~9.20, distance modulus (m-M)v =0.6516, reddening E(B V)=0.26±0.28, and metallicity [Fe/H] = −0.26, respectively. The stars in NGC 7789 show very little movement on proper motion and might be caused by fainter observations.