In order to understand the influence of the elasticity of the floating structure on the mooring tension, a coupling analysis of the mooring system of the floating structure is conducted based on the idea of finite element and lumped mass method, the motion response of the elastic floating structure and the tension of the mooring line are studied, the relevant program is compiled, and the result obtained is compared with that of the related test to verify the accuracy of the program. Taken an elastic very large floating structure as an example, a related mathematical model is established. In a regular wave, the maximum mooring force of 8 mooring lines under different elastic moduli and wave frequencies is calculated. The studies show that: the maximum mooring force increases with the increase of the wave frequency and elastic modulus of the floating structure before the wave frequency reaches resonance frequency; the maximum mooring force decreases with the increase of the wave frequency and elastic modulus of the floating structure after the wave frequency reaches resonance frequency.