The invention discloses a stannic oxide modified ferroferric oxide / multiwalled carbon nanotube network composite material, and a preparation method and application thereof. The preparation method comprises the steps that 1, a ferroferric oxide / multiwalled carbon nanotube is prepared, wherein the multiwalled carbon nanotube is acidized and mixed with ethanediol, ultrasonic dispersion is carried out, then, Fe(NO3)3.9H2O and NaAc.3H2O are added, a reaction is carried out at 200 DEG C for 10 h, aftertreatment is carried out, and the ferroferric oxide / multiwalled carbon nanotube is obtained; 2, stannic oxide modification is carried out, distilled water and SnC14.5H2O are added into the ferroferric oxide / multiwalled carbon nanotube, the mixture is sufficiently stirred to be dissolved, stronger ammonia water is dropwise added after complete dissolving, the pH is adjusted to be 10, a reaction is carried out in a reaction kettle at 160 DEG C for 18 h, and aftertrement is carried out, so that the stannic oxide modified ferroferric oxide / multiwalled carbon nanotube network composite material is obtained.