A latch assembly includes a base having two sidewalls each having first and second guiding slots. A latch is pivotably connected to the base. A follower plate is movably received in the base and includes two sidewalls each having a restraining slot and an engaging notch. A safety plate is mounted between the sidewalls of the follower plate. A pin extends through the first guiding slots of the base, the restraining slots of the follower plate, and the safety plate. A positioning pin extends through the second guiding slots. A spring is attached between the positioning pin and the pin. When latch moves from a latching position to an unlatching position, the positioning pin moves along the second guiding slots of the base under action of the spring and engages with the engaging notches of the follower plate to retain the latch in the unlatching position.