Conventional guar gum fracturing fluid system is defective for its high content of residue,damage to formation /propped fracture,low ratio of flow-back and high costs. To solve these problems,this paper presents a new ultra-low concentration guar gum fracturing fluid,based on the critical overlap concentration of guar gum required for crosslinking. The results of lab test and field application show that the new fracturing fluid system is capable of withstanding temperatures of 95℃,with the content of residue after gel breaking of 172 mg / L,the damage rate of 15% ~ 22%,and the ratio of flow-back of 43. 90% ~ 99. 80%. It is effective for enhanced recovery. So,it is worthy of promotion for wonderful economic and social benefits.