A board-to-board connector assembly has a female connector and a male connector. The female connector has a first insulative housing, multiple first terminals and a latching bar. The first insulative housing has a locking recess and a releasing recess. The latching bar is mounted pivotally on the first insulative housing and selectively engages the locking recess or releasing recess. The male connector has a second insulative housing, multiple second terminals and two latched elements. The latched elements are mounted in the second insulative housing and each latched element has a latched hole selectively engaging with the latching bar to prevent the male connector from falling out of the female connector.