A linear actuator includes a driver (1), a transmission rod assembly (2), a mechanical motion conversion assembly (3) linked between the driver (1) and the transmission rod assembly (2), and a housing (4) covered onto the driver (1), the transmission rod assembly (2), and the mechanical motion conversion assembly (3). The housing (4) includes a lower part (40) and an upper part (41), and the lower part (40) sequentially includes a first containing portion (400) for receiving and installing the driver (1), a second containing portion (401) for receiving and installing the mechanical motion conversion assembly (3), and a third containing portion (402) for receiving and installing the transmission rod assembly (2), and the upper part (41) is covered on top of the first and second containing portions (401, 402), and the first, second and third containing portions (401, 402, 403) are integrally formed as a whole.