Parton distribution functions (PDFs) are important quantities that characterize the structure of hadrons at high energy. Calculating them from first principles has been a long standing challenge in hadron physics and particle physics. In the past few years, rapid progress has been made in directly computing PDFs from lattice QCD. Here I summarize the current status of lattice calculation of PDFs. The state-of-the-art lattice results on nucleon PDFs have shown a reasonable agreement with phenomenological results extracted from the experimental data.