Entangled state of trapped ions has many very important applications in quantum computation and quantum information. Due to the characteristics of quantum systems, the occurrence of laser intensity fluctuations is inevitable, and it has significant influence to the entanglement of trapped ions. With the anti-model of J-C, the effect of intensity fluctuations on dynamics of entanglement of system was studied by computing concurrence and a rough comparison between the model of J-C and the anti-model of J-C was also discussed. The result shows that the noise caused by intensity fluctuation makes the entanglement of two ions weaken with time similarly in an exponential way. The difference of entanglement of system between the model of J-C and the anti-model of J-C is obvious in a weaker laser field.