A novel method of optical voltage sensing based on second harmonic generation in periodically poled LiNbO3 (PPLN)is proposed. The influences of length and duty ratio of PPLN on the performance of optical voltage sensor are discussed. The simulated results show that when the length is fixed, the highest sensitivity can be obtained when the duty ratio is equal to 0.3 or 0.7; and voltage measurement range reaches maximum as the duty ratio approaches 0.5; the sensitivity increases and the sensing voltage measurement range decreases when the length of PPLN increases. These results provide another way to fabricate well-working optical voltage sensor.