Abstract: The remote-control variable diameter stabilizer developed is unreliable in the state signal,resulting in the fact that its state cannot be identified.In order to identify relevant factors affecting the state signal,the stabilizer action was analyzed for changing its diameter under both surface and downhole conditions based on the principle of liquid incompressibility and force equilibrium.Later,combined with its structural characteristics,the result of the analysis was partially verified by field test.The stabilizer can achieve state control by using well deviation signal from the MWD instrument and determine the working state by analyzing the pump pressure difference between two adjacent pump startups.The result of the analysis suggested that the upper and lower position limits of balance piston inside the stabilizer can reduce the action stroke for changing diameter.The field test showed that the state change of the stabilizer conforms to the changing regularity of controlling piston extension and alignment,the pump pressure on piston extension is higher than that of piston alignment,and the absolute difference of adjacent pump pressure is about 1.0 MPa.The working state of the stabilizer can be determined based on the pump pressure value of the second pump startup.The research results showed that,the upper and lower limits of the balance piston position inside the stabilizer would result in a weak state signal or no signal.The method to determine the stabilizer state according to pressure difference between two adjacent pump startups is reliable,and can provide the basis for remote control of stabilizer on the ground.