In view of the problem of frame synchronization in atmospheric laser communication and based on channel characteristics and central limit theorem, two kinds of frame synchronization recognition algorithms are proposed. At first, the atmospheric laser communication channel characteristics are analyzed and the corresponding channel model is established. And then, followed by this model, the data distribution of the output level matrix for each column is discussed, and the frame synchronization algorithm based on the channel characteristics is proposed. At end, aiming at less numbers of matrix frames of the output level, from the probability distribution of the sum value of the output level matrix, the frame synchronization algorithm based on the central limit theorem is proposed. The simulation results show that the performance of the frame synchronization algorithm based on channel characteristics is great on the condition of more number of frames. When SNR reaches 6 dB, the frame synchronous recognition rate can reach 100%, and when the frame number getting small, the frame synchronous recognition rate decreases rapidly. But the number of frames has little effect on the performance of the frame synchronization algorithm based on the central limit theorem. When the SNR is more than 7 dB, even if the number of frames drops to 20, the frame synchronous recognition rate can still reach 100%, which has better frame synchronous performance.