High precision, high resolution and absolute position are the key characteristics for linear displacement measurement.This paper proposes an absolute linear displacement sensor which is suitable for harsh environment. The sensor has a primary coil and a secondary coil.The primary coil is composed of two arrays of spiral coils which are arranged orthogonally.The primary coil is supplied with 4 kHz alternating current to generate two arrays of magnetic field that travel orthogonally. Meanwhile, the spatial periods of the magnetic fields are N and (N+1). The secondary coil consists of two sets of spiral coils, and every set of spiral coils induce only one array of magnetic field.With the motion of the secondary coil, two roads of signals are induced. According to the phase comparison, the absolute position is determined.The structure and working principle of the sensor is proposed. The sensor model is simulated by finite element analysis software. A sensor prototype is fabricated to be verified by experiment. The experimental results show that the measurement range is 61.5mm with the linearity 0.54%.