This paper studies the effect of the lightning leader slant on the shielding angle of the air terminal. The lightning leader is modeled by using discrete line charges. The Rizk voltage condition is assumed as the upward lightning leader condition which is the lightning stroke condition to the lightning rod. The attractive radius and the shielding angle of the air terminal are calculated for different air terminal heights, different lightning currents and different lightning leader slopes. The calculated results show that the attractive radius of air terminal depends on the rod height, the lightning current and the lightning leader slope. A formula related between the lightning current, the lightning leader slope, the attractive radius and the air terminal height is proposed. The slant of lightning leader decreases the air terminal shielding angle, especially at low lightning current and long air terminal.