A curtain body locating mechanism for use in a curtain with no cord comprises a fixed base, two first driving wheels, two second driving wheels, two movable shafts and two resistance wheels. The first driving wheels are disposed on the fixed base and connected together by a coil spring, and the second driving wheels are disposed on the fixed base and engaged with the first driving wheels. Each of two driving ropes is connected to each of the second driving wheels, and the two movable shafts are disposed on the fixed base movably in the horizontal direction and are connected together by a tension spring. The resistance wheel is nested onto the movable shaft rotatably and is surrounded by one of the driving ropes.