A trough rail and I-rail connecting structure and welding method are disclose, A connection structure includes a slot rail, I-rails and special-shaped transition rails, the height of rail head of the-groove rail, special-shaped transition rail and I-rail is equal and the direction of working edge is the same, the special-shaped transition rail comprises a groove-shaped rail section, transition section and I-rail connection section, As that shape of the groove track segment is the same as that of the groove track, the I-rail connecting section is connected with the I-rail by welding, The groove-shaped rail section is welded with the groove-shaped rail, the rail waist of the I-shaped rail is not coplanar with the rail waist of the I-shaped rail connection section, different sides of the rail waist of the I-shaped rail and the rail waist of the I-shaped rail connection section are respectively welded with reinforcement plates at the connection ends, and the end faces of the reinforcementplates are respectively welded with the corresponding rail waist. The strength of the invention is basically unaffected, and the invention has better reliability compared with the prior art. At the same time, because the direction of the working side is consistent, the stability of the vehicle is good when it runs through.