The utility model relates to a belt-conveyor transmission device with a randomly-turning function within the range of a vertical angle, which is characterized by comprising two groups of belt conveyors, wherein one end of a first group of belt conveyors is provided with a main driving wheel driven by a motor, the other end of the first group of belt conveyors is provided with a main transmission wheel and two guide wheels, and a belt-conveying loop is formed by surrounding the main driving wheel, the main transmission wheel and the two guide wheels by a belt of the first group of belt conveyors; and one end of a second group of belt conveyors is provided with a slave transmission wheel, the other end of the second group of belt conveyors is provided with an output driven wheel, another belt-conveying loop is formed by surrounding the slave transmission wheel and the output driven wheel by a belt of the second group of belt conveyors, and the main transmission wheel is connected with the slave transmission wheel through a conveying belt. Through the belt-conveyor transmission device, the belt conveyors can turn at any angle within the range of the vertical angle between leftwards turning at 90 degrees and rightwards turning at 90 degrees and can be repeatedly used, so that the expenses for purchasing a turning belt conveyor can be reduced, the investment of belt-conveyor equipment is reduced, the transportation cost of the belt conveyor is saved, and the cost is lowered. The belt-conveyor transmission device has a simple structure, is convenient to install and regulate and can be widely applied to tunneling and coal mining.