Abstract: Laser direct writing (LDW) is a highly efficient and scalable technology to fabricate flexible electronic devices. In this work, a type of flexible circle antenna sensor is developed by LDW on polyimide film with good dielectric property in response to strain and humidity. The carbonized polyimide has good conductivity and great adhesion to the substrate, which could be used as the active material for antenna. The carbonized polyimide presents porous stacked carbon structures and has the excellent electrical properties, which facilitate strain sensing and make the antenna have low loss, respectively. The resonance frequency of the LDW-generated antenna sensor changes with the variation of applied strain and environmental humidity. The sensitivities of LDW-generated antenna sensor response to applied strain and humidity are −8.943 kHz/με and −6.45 MHz/RH%, respectively. The flexible antenna sensor prepared by the LDW provides a new possibility for the application of structural health monitoring.