Bandgap properties of disordered one-dimensional (1D) ternary photonic crystals are investigated by optical transfer matrix method for the first time . The results show that disordered structure provides strikingly extended bandgap compared with the corresponding periodic structure. The more ingredient of disordered dielectric multilayers adopted in the calculation, the wider stop band will be obtained. The influence of degree of disorder D and contrast of high and low refractive indices to the photonic bandgap are also calculated and discussed.