The invention relates to the technical field of 
chemical plating, in particular to an activator, a preparation method and a preparation method of 
carbon fiber composite material. The activator is prepared from the following components of a dispersing agent, 
sodium citrate, 
nickel salt and a 
boron-containing compound, wherein the 
boron-containing compound is 
potassium borohydride or 
sodium borohydride, and the PH value of the activator is 9-11. The dispersing agent in the activator can prevent aggregation of 
carbon fibers in water solution and re-aggregation after the 
carbon fibers are activated and washed, the activator has a procedure integrated function, the 
carbon fibers are only needed to be placed in the activator, the procedures of dispersing, sensitizing and activating of the carbonfibers can be completed, so that traditional complicated steps of dispersion, 
sensitization and activation are simplified. The activator exists in an alkaline condition and is relatively high in stability, so that the activating effect is good, the 
chemical plating rate is high, and the practicability is good. In addition, the activator uses cheap and easily available 
nickel instead of 
noble metal palladium or silver, so that the activation cost is saved.