Second harmonic generation microscopy (SHGM) has been widely used in biomedicine as a promising non-invasive imaging technique. However, due to the complexity of biological samples, false images are often produced depending on sample orientation relative to laser polarization and on sample parameter related to the second-order optical nonlinear susceptibility. In this work, we present a convenient SHG technique to correct the false images by modulating laser polarization and stitching complementary images together, the stitched image will contain more detailed information and will better represent the sample structures. We first describe our SHG technique with a brief mathematical model, and then show its validity by performing it on two kind of samples: symmetrically synthesized bio-origin polymer poly(3-hyroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and fibrillar collagen of rat-tail tendon.