The cold inplace reclaimed composite base technique is a technique that the partially old asphalt pavement and the partially old base was milled together then reclaimed inplace as a new base with flexible and rigid property. Taking the treatment project for failed asphalt pavement of Yuhu Expressway in Chongqing as a case study, the structure thickness and the structure composition, the material parameters, the technological parameters were studied and mechanic behavior was discussed for the cold inplace reclaimed composite base. It is found that (1)based on milling and reclaiming asphalt concrete with upbase stabilized by cement together, a suitable compacted thickness should be controlled within the 26cm to ensure the compaction quality for the cold inplace reclaimed composite base,;(2)the void contents for the cold reclaimed composite base would be restricted at low than 12%;(3)a waterproof layer should be set and the thickness of new asphalt concrete should be paved to be more than 9cm on the cold inplace reclaimed composite base;(4)the principal technical performances are recommended using the Marshall Flow(to be controlled in the range of the 3～5 mm)、soaked split strength(to be large than 0.45 MPa)、the freezethaw split strength ratio(to be large than50%) and the bend strain( to be large than 1 800 με) as the controlled index of the cold reclaimed composite base. And the dynamic stability(to be large than 2000 times/mm)only is used as a secondary technical performance.