The invention relates to high anti-cracking and high anti-penetrating composite material for concrete and the preparation method thereof, and contains the following components according to the weight ratio: expansion agent of 80 to 99 percent, synthetic fibre of 0.5 to 4.0 percent, water retention agent of 0 to 4.0 percent and water reducing agent of 0 to 12 percent. The preparation method comprises the steps as follows: mixing the components till the coefficient of dispersion of the distributed synthetic fibre is less than 0.03. The invention having the advantages of simple preparation method and low cost greatly simplifies the production art of the concrete and brings higher anti-cracking and anti-penetrating abilities of the concrete.