The invention relates to a bridge arch segment right-angle turning method. The bridge arch segment right-angle turning method specifically includes the following steps that firstly, two axis flatcars of the same size and the same specification are selected, and according to the size of arch segments, buttresses with the height gradually increased are evenly laid above the bearing axis of each axis flatcar; secondly, a left truss sheet of each single arch segment is arranged on the buttresses of the first axis flatcar through a crane, and a right truss sheet of each single arch segment is arranged on the buttresses of the second axis flatcar through the crane, so that the arch segments are fixed to the axis flatcars through the buttresses, and at this moment, the left truss sheets and the right truss sheets of the arch segments are almost perpendicular to the direction of a transport ship; thirdly, after the arch segments and the axis flatcars are fixed, the two axis flatcars are steered in a splayed manner in situ, and the operation is conducted repeatedly till the arch segments are turned by 90 degrees; and fourthly, after the arch segments are turned, the turned arch segments are loaded to the ship through the crane in the direction of the transport ship. The bridge arch segment right-angle turning method has the beneficial effects that operation is convenient, investment is small, safety and reliability are achieved, and efficiency is high.