This paper presents a lateral thermally-actuated and laterally capacitive shunt MEMS switch utilizing parylene as the dielectric layer. The bulk maicromachined switch consists three parts which, including coplanar waveguide (CPW) line, switching plates and thermally actuated structures. Measured results show that the threshold driving voltage and current of the proposed switch are 11.5V and 95mA, the single side and both side isolations at close-state are 7.7dB and 10.2dB at 18GHz when parylene thickness is 530nm, respectively. With 80nm- thick parylene, the single side and both sides isolations are 11.2dB and 15.7dB at 18GHz, respectively. The insertion loss at open-state is below 0.26dB up to 18GHz, when a boding wire is used to bridge the ground line.