The invention discloses a bilateral laser-InFocus electric arc composite welding method for a T-type joint, and relates to a welding method. The method comprises: I, processing a to-be-welded part and fixing the to-be-welded part by a clamp; II, keeping an included angle alpha between an InFocus welding gun and a panel longitudinal surface of the T-type joint at 30 degrees to 45 degrees, and keeping an included angle beta between the InFocus welding gun and a T-type bottom plate at 30 degrees; III, setting bilateral laser power to 1000W-3000W, setting bilateral electric-arc current to 200A-900A, setting gas flow of an electric-arc welding gun to 15L/min to 30L/min, and setting welding speed to 1.0m/min to 5.0m/min; and IV, implementing welding. Compared with the peak value of conventional ITG electric arc 400A, current acting force and energy density are relatively large, key hole welding can be realized, depth of fusion is large, welding speed is high, and welding efficiency is improved; during welding of a medium-thickness plate, laser power is reduced by increasing welding current, so that the welding cost is reduced.