Abstract: The soliton source is the key element in the soliton communication system.In order to search the satisfying soliton source in the low loss fiber of the soliton communication,the disturbed nonlinear Schrdinger equation of the ultrashort optical pulses was derived in response to the property of pulse in the Cr4+:YAG laser,the influence of dispersion and gain and loss and nonlinear effect on the fundamental soliton was analysed in the cavity in system,the relation between the configuration of the cavity and the parameters of the fundamental soliton was discussed.It is proved that the generation of the fundamental soliton in the Cr4+:YAG laser,and the Cr4+:YAG laser may be the soliton source of the soliton communication system.