The nonlinear problem is very important to float flow sensor, which affects accuracy of rotameter. In order to solve the problem, the characteristics of float flow sensor are studied and the relationship between float height and flux is analyzed by least square method. The obvious nonlinear relationship between flux and float height to short-pipe type float flow sensor is presented. It is found that the linearity could be improved by increasing the float distance of run and decreasing the taper angle, which...