A modular actuator (1) includes an actuation module (10), a gear module (20) and a telescoping module (30). The actuation module (10) includes a motor (11) and a drive worm (12) driven by the motor (11). The gear module (20) includes a gearbox (21) and a deceleration gear assembly (22) disposed in the gearbox (21). The deceleration gear assembly (22) includes a deceleration worm gear (221) engaged with the drive worm (12) and includes a deceleration worm (222) driven to rotate by the deceleration worm gear (221). The telescoping module (30) includes a drive worm gear (31), a lead screw (32) driven to rotate by the drive worm gear (31), and an extendable pipe (33) threadedly connected to the lead screw (32). The drive worm gear (31) is engaged with the deceleration worm (222), and the lead screw (32) is arranged parallel to the drive worm (13).