The invention discloses a method for starting a motor without a position sensor, which includes: applying a fixed voltage vector to the motor and obtaining Is; subjecting the Is to Clark conversion and obtaining i <alpha> and i <beta>; presetting rotation speed omega r and torque T<e> as 0 by computing to obtain rotor flux-linkage vector angle theta r, subjecting omega r and omega r to PI operation to obtain Te, then subjecting Te and the T3 to PI operation to obtain delta, obtaining theta<s> according to the formula theta <s>=theta <r> +delta, giving Psi* <s> to obtain U<alpha> and U<beta>, subjecting the U<alpha> and the U<beta> to inverse Clark conversion and obtaining U, U and U<c>, acquiring I, I and I<c> through current, subjecting the I, the I and the I<c> to Clark conversion and obtaining I alpha and I beta, obtaining Psi <s> alpha and Psi<s> beta by stator flux linkage operation, obtaining Psi<s> and theta<s> by modular angle operation, obtaining the Te by torque estimate, discretizing the theta<s> to obtain omega<r>, and finishing motor starting process if the omega<r> is equal to the omega*<r>. The method for starting the motor without the position sensor has the following advantages that by combining initial position detection technology with DTC (direct torque control) strategy, loop-locked stable control of the integral control strategy is realized.