The invention discloses a separation and enrichment method for lithium isotopes. The method comprises the steps that S1, an extracted organic phase is prepared, wherein a crown ether derivative represented as the formula A or the formula B is taken as an extraction agent, and the extraction agent, hydrophobic ionic liquid and a diluent are mixed to obtain the extracted organic phase; S2, an extracted water phase is prepared, wherein water-soluble lithium salt is prepared into a lithium salt solution, and the lithium salt solution is taken as the extracted water phase; S3, after the extracted organic phase and the extracted water phase are fully mixed and extracted, phase splitting is conducted, and a load organic phase and extraction raffinate are obtained; S4, the load organic phase is burned for 30-200 min at the temperature of 400-1,000 DEG C, and a slag phase is obtained; S5, the slag phase is dissolved with water, solid-liquid separation is conducted, and 6Li enrichment liquid isobtained; S6, the 6Li enrichment liquid is taken as the extracted water phase, and the steps of S3-S5 are repeated. The invention provides a brand new technology method without adopting the reverse extraction operation based on a crown ether extraction system. The technology method is a quick cross flow superposing multi-level cascade separation method capable of enriching the methods of conducting separation and enrichment treatment on lithium isotopes.