<p>Piezoelectric 1–3 composites have been widely used in fields of medical ultrasound, non-destructive evaluation, and hydroacoustic etc. due to their excellent acoustic and electromechanical capabilities. Here, effective properties of epoxy-based piezoelectric 1–3 composites with a varied piezoelectric ceramic volume fraction and thickness were discussed based on finite element analysis (FEA) accompanied by experimental verification. The research results show that the relative permittivities at constant stress of piezoelectric 1–3 composites increase with increasing piezoelectric ceramic volume fraction, and are basically independent on thickness of the composite. The piezoelectric strain coefficients <i>d</i>₃₃ of piezoelectric 1–3 composites show an increasing trend with increasing piezoelectric ceramic volume fraction; however, the piezoelectric voltage coefficients <i>g</i>₃₃ show an opposite variation. There exists a linear relationship between thickness resonance frequency and reciprocal of thickness, and the frequency constant of the composite is 1152.46 when piezoelectric ceramic volume fraction is 67.82%. The thickness electromechanical coupling factors <i>k</i>_t of piezoelectric 1–3 composites are far larger than that of the piezoelectric ceramic, and their acoustic impedance and mechanical quality factor are obviously lower than those of the piezoelectric ceramic. Therefore, the epoxy-based piezoelectric 1–3 composite with desired electromechanical coupling properties can be tailored by changing piezoelectric ceramic volume fraction and thickness.</p>