A treatment method and application for laterite nickel ore leaching solution with high calcium and magnesium content, comprising the following steps: S1. preparing an extracted organic phase from the 2-hexyldecanoic acid and the HBL110/HBL116 extractant; S2. performing nickel-cobalt co-extraction on the extracted organic phase and a laterite nickel ore leaching solution with a high calcium and magnesium content to obtain a first loaded organic phase and a raffinate; in a laterite nickel ore leaching solution with a high calcium and magnesium content; S3. washing the first loaded organic phase with a washing solution to obtain a second loaded organic phase and washing water, wherein the washing water is refluxed to a laterite nickel ore leaching solution with high calcium and magnesium content; S4. adding a reverse extracting solution to the second loaded organic phase for reverse extracting to obtain a nickel-cobalt salt solution and a reverse extracted organic phase; S5. saponifying the reverse extracted organic phase to obtain a regenerated extracted organic phase; this scheme is applicable to the environment with high calcium and magnesium, can prevent calcium and magnesium from forming a third phase, and the effect of separating and purifying nickel and cobalt is good.