Objective: The purpose of corn improvement is to develop inbred lines and new hybrids to improve the existing cultivars according to different traits. Success in the commercial production of hybrid corn depends on the extensive evaluation of inbred lines. Methods: This research was carried out in order to determine the superior line, tester and hybrid of grain corn using the line x tester analysis method in the agricultural year of 1401 on the farm of Khoy Agricultural Research Station. Results: Lines L6 and L7 were the first lines for the number of days to physiological maturity, and hybrids T1×L18, T2×L23, and T3×L3 had the most special adaptation. Conclusion: Based on this, Lines L6 and L7 were the earliest ones for the number of days until physiological maturation. Also, T1×L18, T2×L23, and T3×L3 crosses had the highest specific compatibility.