With the development of ultra high-vollage technology in our country, the measurement of intensive power frequeney cleetricfield has become more and more important. In order to suit the measurement reruirement of the intensive power frequency electrie field,based on the Poeckels effeet, a polarization-maintaining fiber eoupling type lithium niobate crystal intensive power frequeney electrie fieldsensor is designed, fabrieated and experimentally investigated, The optical input and output of the sensor are carried out through thecoupling of the polarization-maintaining fiber(PMF) collimators, which avoids the use of polarizer, 1/4 wave plate and other separatedoptical components. As a reult, the optical coupling efficieney of the sensor is improved to 66.7%。In addition, through twisting thePMF at 1/2 beat length in the font end of the input PMF collimator by 90°, the static operating point of the sensor can be set to m/2,which makes the sensor work in the nearly linear region. The intensive power frequeney electrie field was used to test the input/outputcharacteristics of the sensor. It is concluded that the linear measurable range of the sensor is 10.5~527 kV/m, the linear correlationcoeficient is 0.9986 and the linear dynamic range is 34 dB. Compared with the existing lithium niobate erystal intensive electrie fieldsensor, the sensor developed has the advantages of simple and compaet structure, and high coupling efficieney, which provides a newsolution for the measurement of power frequency intensive electric field in the time domain.