The invention discloses an improves construction technology of a CFG (cement fIying-ash gravel) pile, which is characterized by comprising the following steps of: A, punching and plunging a pile pipe; B, arranging a high-pressure grouting pipe into the plunged pile pipe, and adding aggregates, wherein the aggregates can be gravels or mixed materials of gravels and sands which are prepared in proportion; C, pulling the pile pipe out, and tamping the aggregates inside a hole; D, building a plurality of pile points on a plurality of piling positions by repeating the steps; E, cleaning the hole of each pile point and grouting the hole of each pile point by pressure, i.e. firstly injecting water into the hole through the high-pressure grouting pipe, and cleaning the hole and the aggregates inside the hole till clear water overflows out of an orifice; and then grouting pulverized fuel ash cement paste or pulverized fuel ash cement plaster into the hole filled with the aggregates by using the high-pressure grouting pipe till grouts are burst out of the orifice. The invention can effectively enhance the carrying capacity of the CFG pile and the bonding degree of the pile and soil bodies and effectively prevent the defects of necking down, pile breakage and pile body clamping soil, has extensive application, and can be suitable for various geological conditions.