A static frequency converter start-up control strategy for pumped-storage power unit is presented. Rotor position detection without position sensor is realized through voltage and magnetism equations of mathematical model of an ideal synchronous motor. The mechanism and implementation method of initial rotor position determination and rotor position estimation under low frequency without position sensor are expounded and validated by simulations. Based on the proposed control strategy， a static frequency converter start-up device for large-scale pumped-storage unit is developed， and applied to start-up control test in the 90 MW generator/motor of Panjiakou pumped-storage power plant. Test results show that rotor position detection， pulse commutation， natural commutation， and unit synchronous procedure control of static start-up have all been achieved. The outcomes have been applied to running of field equipment， which proves the feasibility of mentioned method.