Abstract: Chaotic sequence, which is more secure and diverse in form, can be used as spreading code in spread spectrum systems. A new random sequence for spectrum spreading was introduced by piecewise conjugate augment of Skew Tent map into a new construction method which could greatly improve the weak chaotic property of traditional Skew Tent map random sequence, especially in the aspects of randomness and correlation. Simulation results show the new map construction method has better sequence chaotic property and achieved lower BER (Bit Error Rate) than traditional one. Improved piecewise Skew Tent map, as the encryption algorithm for image communication system, has improved the quality and safety of the image information effectively. Piecewise conjugate augment of Chaos Map which can improve the weak chaotic property, is an effective construction method, and the better chaotic property Chaos Map will broaden the application of spreading communication in military and civil field.