In order to investigate the influence of terahertz polarization-maintaining waveguides on the transmission signal of the terahertz communication systems,we propose the power budget model of waveguide links.The effects of the parameters (length,loss,dispersion,and birefringence) of polarization-maintaining subwavelength dielectric waveguides on the communication performance of amplitude shift keying (ASK) modulation systems are investigated.We calculate the received power,signal-to-interference-plus-noise ratio (SINR),coherence and incoherent demodulation bit error rate (BER) of two orthogonal polarization state signals for different transmitting power,waveguide lengths,modulated signal characteristic time widths,and modulated signal periods.The results show that the communication system can achieve high-speed (3.33 Gbit/s) and low BER (less than forward error correction limitation,10-3) by designing the waveguide structure.This work reveals the influence of length,loss,group velocity dispersion (GVD) and birefringence of terahertz subwavelength waveguides on communication performance,which has positive significance for the development of broadband communication systems based on terahertz waveguide links.