We developed a growth model for Panulirus ornatus by measuring the length of individuals during different growth periods during rearing in the laboratory. Growth was explained by the following equation: W= 0.035 8× L3.043 2. The body immortal length was explained by the equation Lt=56.0×[1-e−0.053 1(t−1.1944)]. The relationship between body length and carapace length was L=2.772 2CL + 0.337 9. The body weight growth equation was Wt= 7 481.2×[1-e−0.0531(t−1.1944)]3. The rate of change in body immortal length was explained by Dl/Dt=56.0×0.0531× е−0.0531(t−1.1944). The rate of change in body weight was explained by dW/dt=3×7 481.2×0.053 1×е−0.053 1(t−1.1944)× [1-е−0.053 1(t−1.1944)]2 . The inflection point age of P. ornatus was 14.56 months, calculated using the formula Tr = ln3/K+t0. Body length increased more rapidly during the early period. Conversely, body weight increased more rapidly in the later period. The body weight growth curve was represented by an asymmetrical S curve, but had an inflection point. The body weight increased up to a maximum of 79.24 g•month−1 at the inflection point.