The invention provides a nuclear magnetic resonance contrast agent. According to the technical scheme, by aiming at the problem of low relaxation rate caused by generally using heavy metal compounds as main ingredients in the prior art, the ingredients of the contrast agent are redesigned, an organic matter with low molecular weight is used for replacing heavy metal salt; meanwhile, chiral compounds of levamisole hydrochloride are added so as to improve the polarizing coefficient. On the basis, in order to improve the attachment force of the contrast agent in the body, the viscosity is obviously improved through Arabic gum and glycerol tricarboxylate; the texture of the formed cross-linking substances is uniform; stable and clear images can be formed. The contrast agent provided by the invention has the advantages that different cancer tumors can be detected through grafting with different magnetic groups; meanwhile, the contrast agent can be efficiently enriched onto the tumor cells, so that the positive effect is achieved on the early stage diagnosis of cancer. The obvious technical effect is achieved by the ingenious technical design; meanwhile, the cost is lower; the realization is easy, so that good popularization prospects are realized.