Abstract: In order to study the effects of symbiotic period on plant traits and yield of rapeseed planted with ratooning rice, 5 treatments of symbiotic period of ratooning rice and rapeseed were as designed separately:0 (T1), 3d (T2), 5d (T3), 7d (T4) and 10 d (T5). The results showed that:(1) Rapeseed yield had a clear second-degree parabola relation (y=-8.98x²+93.817x+1 864.6, R²=0.848) with symbiotic period, the maximum was 2 179.8 kg·hm^-2 in T3 treatment. (2) With the prolonged symbiotic period of ratooning rice and rapeseed, the rapeseed density in seedling period continuously increased, but rapeseed density in bud period and blossom period reduced after the first increased. The density size of stable rapeseed was T3>T2>T1>T4>T5. (3) Symbiotic period was extremely correlated with the first effective branch number, effective pod number of main raceme, productive pod number of branch, productive pod number of plant, biomass per plant and yield per plant (p<0.01), respectively, which was significantly negatively correlated with seed number per pod and plant density, while was not significantly associated with the 1000-grain weight and effective pods of main raceme. Different treatment of symbiotic period on rapeseed planted with ratooning rice influenced rapeseed yield by plant yield, yield per plant and other relevant indexes. Therefore, suitable symbiotic period was conducive to rapeseed yield formation.