Semiaromatic polyamides containing thioether units were synthesized through the reaction of 4,4'-thiodibenzoyl chloride (TDC) and diamine by the method of interfacial polycondensation. The inherent viscosities of the resultant polyamides prepared with optimum synthesis conditions were 1.08-1.26 dL/g. These polyamides had excellent thermal properties with glass transition temperatures (T-g) of 119.8-190.1 degrees C, melting temperatures (T-m) of 281.4-355.5 degrees C, and initial degradation temperatures (T-d) of 433.5-466 degrees C. They had wider processing windows than traditional semiaromatic polyamides. At the same time, they had better tensile strengths of 62.1-86.5 MPa, better low-temperature mechanical properties, lower water absorption, lower dielectric constants of 3.16-3.81 at 100 kHz, and better melt flowability properties. The results suggest that these semiaromatic polyamides containing thioether units [poly(hexanelene 4,4'-thiodibenzoamide) (PA-6), poly(octanelene 4,4'-thiodibenzoamide) (PA-8), and poly(decanelene 4,4'-thiodibenzoamide) (PA-10)] represent a promising type of heat-resistant and processable engineering plastic.