NOVELTY - A carbon nano-tube grafted glass fiber multi-scale reinforcement reinforced bismaleimide composite material preparation method involves mixing dry carbon nano-tube and inorganic acid to obtain a mixture. The mixture is reacted by heating to obtain a reacted product. The reacted product is diluted. The diluted product is filtered using micro-porous filtering film. The filtrate-I is washed using de-ionized water until the filtrate becomes neutral. The diluted filtrate is dried under vacuum to obtain purified carbon nanotube. The obtained nanotube is heated with strong oxidizing acid.    USE - Method for preparing carbon nano-tube grafted glass fiber multi-scale reinforcement reinforced bismaleimide composite material for use in aerospace, transport and communication trade, wind power generation and mechanical and electronic field.    ADVANTAGE - The method enables improving interface bonding strength of the composite material in simple manner.    DETAILED DESCRIPTION - A carbon nano-tube grafted glass fiber multi-scale reinforcement reinforced bismaleimide composite material preparation method involves mixing dry carbon nano-tube (0.1-1/asterisk10g) and inorganic acid (10-1/asterisk104mL) under ultrasonic wave of 120 kHz at speed of 10-106r/min for 0.1-24 hours to obtain a mixture. The mixture is reacted by heating at 20-150 degrees C for 1-48 hours to obtain a reacted product. The reacted product is diluted. The diluted product is filtered using micro-porous filtering film. The filtrate-I is washed using de-ionized water until the filtrate becomes neutral. The diluted filtrate is dried under vacuum at 25-150 degrees C for 1-48 hours to obtain purified carbon nanotube. The obtained nanotube (0.1-1/asterisk10g) is heated with strong oxidizing acid (1-1/asterisk103 mL) under ultrasonic wave of 120 kHz at 25-120 degrees C for 0.1-80 hours. The obtained product is refluxed for 1-80 hours. The refluxed product is diluted by washing in de-ionized water. The diluted product is filtered by using super micro-porous filtering film. The filtrate-II is washed using de-ionized water until the filtrate becomes neutral. The neutralized filtrate is dried under vacuum at 25-200 degrees C for 1-48 hours to obtain acidified carbon nanotube. The acidified nanotube (0.1-1/asterisk10g) is uniformly dispersed in organic solvent (1-1/asterisk103 mL) by mixing at 5-120 degrees C under ultrasonic wave of 1-120 kHz for 1-24 hours . The dispersed mixture is reacted with dry glass fiber (0.1-1/asterisk103 g) for 1-96 hours, filtered, washed and dried under vacuum at 25-200 degrees C for 1-96 hours to obtain glass fiber multi-scale reinforcement grafted carbon nanotube. The grafted nanotube (0.1-1/asterisk10g) is reacted with coupling agent solution (1-1/asterisk103 mL) at 5-120 degrees C for 1-96 hours and filtered at 25-200 degrees C. The filtrate-III is dried for 0.1-48 degrees C to obtain functional glass fiber multi-scale reinforcement grafted carbon nanotube. The functional glass fiber grafted nanotube (0.1-1/asterisk10g) is reacted with bismaleimide composite material formed by vacuum (1-1/asterisk103 g) to obtain target product.