The invention provides a method and a device for controlling dehydration of a washing machine. The method comprises the following steps of: at the starting of the dehydration, acquiring acceleration data; calculating displacement of an outer barrel of the washing machine according to the acquired acceleration data; judging whether the displacement of the outer barrel of the washing machine is greater than a displacement limit value; when the displacement is not greater than the displacement limit value, judging whether the current rotating speed of the outer barrel of the washing machine reaches a set maximum rotating speed, if the current rotating speed of the outer barrel of the washing machine does not reach the set maximum rotating speed, controlling a motor driving circuit to increase a target rotating speed, and if the current rotating speed of the outer barrel of the washing machine reaches the set maximum rotating speed, keeping the current rotating speed until the end of the dehydration; and when the displacement is greater than the displacement limit value, judging whether the current rotating speed is greater than a set safety rotating speed, if the current rotating speed is not greater than the set safety rotating speed, controlling the motor driving circuit to stop a motor, and if the current rotating speed is greater than the set safety rotating speed, controlling the motor driving circuit to decrease the target rotating speed and keeping dehydrating. By the invention, the shortcomings of the conventional method and the conventional device for controlling dehydration of the washing machine can be solved, so that the washing machine can get higher counter balance and dehydration performance.