A triangular main material cross section power transmission line straight pole tower mainly consists of an upper-portion tower head and a lower-portion tower body and is characterized in that the tower head is mainly composed of left and right straightened crank arms and forms a V-shaped structure with an opening gradually increscent from bottom to top, and a long through cross beam penetrating through the left and right crank arms is arranged at the upper portions of the left and right straightened crank arms and forms a three-phase lead horizontally arranged structure. The middle position of the lower-portion tower body is divided into 4 large split connecting legs extending along the oblique lower portion by a prism frustum structure, and a front side inverted 'V' structure is formed. The left and right crank arms of the tower head and main material cross sections at the connecting legs of the tower body are all triangular cross sections. Each of the left and right crank arms of the tower head is a triangular cone support consisting of two first straight lines symmetrically in a front and back mode and a second straight line located in a central plane on the side. The triangular main material cross section power transmission line straight pole tower has the advantages of being simple in structure, balanced in stress, clear in force transfer, low in cost and high in structural strength, decreasing the number of rods and the like.