A bed frame has a left longitudinal support bar, a right longitudinal support bar and an intermediate longitudinal support bar, two sliding sleeves slidably disposed on the intermediate longitudinal support bar, wherein each of the sliding sleeve is provided with a bracket. The bed frame further comprises four connecting rods connected between the left longitudinal support bar or right longitudinal support bar and the intermediate longitudinal support rod, one end of each of the connecting rods is pivotally connected to the left or right longitudinal support bar, the other end is pivotally connected with the bracket so that the end of the connecting rod mounted on the bracket moves along with the sliding sleeve. The bed frame is simple and easy to fold and un-fold, while providing improved strength and stability.