Abstract: A ceiling light fixture includes a housing forming a channel having a trapezoidal cross section and a light-transmitting cover panel fixed in and covering the channel. The channel has a bottom wall forming a slot. A circumferential mounting frame is formed on a back of the bottom wall of the channel and barbs extend from the mounting frame. The bottom wall further forms a fitting hole. The ceiling light fixture selectively receives a first lamp assembly in the mounting frame and secures the lamp assembly with the barbs so that a light source of the lamp assembly is exposed through the slot for irradiating light or alternatively an end seat of a lamp tube is fit and retained in the fitting hole to set and fix the lamp tube in the slot to realize interchangeable use of the ceiling light fixture with different lamp assemblies.