The invention discloses a high-strength and high-toughness long carbon fiber reinforced nylon composite and a preparation method thereof. The nylon composite is prepared from the following raw materials in parts by weight: 40 to 80 parts of nylon 610, 20 to 30 parts of nylon 6, 20 to 60 parts of long carbon fiber, 0.5 to 1 part of lubricant and 0.1 to 1.5 parts of antioxidant. The high-strength and high-toughness long carbon fiber reinforced nylon composite provided by the invention has the advantages that firstly, long carbon chain nylon is selected as a nylon base material and has low water absorption and high toughness; secondly, the high rigidity of long carbon fiber makes up the insufficient rigidity of nylon 610 and nylon 6; thirdly, the viscosity of a nylon melt can be greatly reduced by adding the lubricant so as to improve the impregnation effect of nylon on carbon fiber; finally, 4, a toughening agent does not need to be added, so that the effect of reduction in mechanical property caused by addition of the toughening agent is avoided.