Pulse-position modulation (PPM) has the advantages of simplicity and high interference immunity but is affected by the issues concerning low frequency band utilization. To improve the system’s bandwidth utilization and data transmission rate, a hybrid modulated faster-than-Nyquist (PSK-PPM-FTN) rate atmospheric optical communication scheme in combination with phase-shift keying (PSK) and PPM is proposed in this paper. The bit error rate (BER) is derived over Gamma-Gamma-distributed atmospheric channel. In addition, the relationship of BER and transmission distance, laser wavelength, and time acceleration factor τ is analyzed. Monte Carlo simulation results show that when high-order PPM is combined with multi-ary PSK, and additional information can be transmitted at the cost of a slight drop in BER performance in a horizontal communication link with τ≥0.8. When τ=0.8, the amount of information, which is transmitted by a quadrature PSK-PPM4 FTN (QPSK-PPM4-FTN) scheme, is 1.5 times than that of QPSK, and the system bandwidth utilization is 150% higher than that of PPM4.