A ceil fan blade assembly includes an upper blade, a lower blade, and a decorative member enclosed between the upper and lower blades. The upper and lower blades are formed with engaging portions which are an engaging rib and en engaging groove to connect the upper and lower blades together. Each of the upper and lower blades is formed with an inner recess at the middle and rear sections thereof so as to enclose the decorative member. The decorative member is made of colored paper, plastic material or embossment board. The upper and lower blades are connected tightly to become one piece after high frequency or ultrasonic process. The surface of the decorative member is printed or carved with a patter to be reflected through the inner recesses. This provides a simply and easy way and is cost-effective.