Time-resolved second harmonic generation is utilized to investigate the photoexcited carrier and phonon dynamics in wurtzite InN nanorods. The exponential decay response in the pump-induced second-harmonic generation curve reveals the carrier relaxation process via radiative and nonradiative recombination channels. Meanwhile, the generation and detection of the coherent A1(LO) phonon can reveal not only the phonon dynamics but also the crystalline quality in InN nanorods. It is found that the nonradiative structural defects play a dominant role in the transport and optical properties of InN nanorods.