In this study, a flexible photonic crystal laser was demonstrated with InGaAsP nano rods on a polydimethylsiloxane (PDMS) substrate. The InGaAsP nano-rods content 4 quantum wells which are designed for 1.55 μm communication wavelength. The lasing action was observed around 1550nm which is a band-edge emission at high-symmetry -point of photonic crystals. One of advantages of the flexible laser is the fine-tuning of optical properties by manipulating its geometry. In this work, we observed the lasing wavelength can be controlled by increasing photonic crystal lattice extension. The lasing wavelength was linearly red-shift up to 6 nm as the lattice extension percentage increased to 2.2%. The wavelength tuning rate is approximately 2.69 nm for 1 % lattice extension. Those geometric fine-tuning properties indicate the flexible photonic crystal laser can be applied as a compact tunable light source in photonic crystal integrated circuits or biomedical sensors.