The invention discloses a nickel chloride (II) chelate taking 1-pyridyl-6-methoxyl-beta-carboline as a ligand, as well as a synthesizing method and application of the nickel chloride (II) chelate. The structural formula of the nickel chloride (II) chelate is as shown in a formula (I); a preparation method for the nickel chloride (II) chelate comprises the following steps: dissolving the compound which is as shown in a formula (II) and nickel chloride hexahydrate in a polar solvent, and performing a complexing reaction to obtain a target product. The nickel chloride (II) chelate disclosed by the invention shows higher anti-tumour activity than the ligand, has a good medicinal value and is expected to be used in preparation of various anti-tumour medicaments. The structures shown in the formula (I) and the formula (II) are as shown in the description.