Photonic systems have become a promising platform for testing quantum principles and implementing quantum simulations. Recently, photonic lattices have been used to simulate conventional topological systems and explore novel topological phases. However, a direct measurement of bulk topological invariants (such as bulk Chern numbers) remains a great challenge. In this talk, I will present our recent results on topological phase transitions and Thouless pumping of light in one-dimensional photonic lattices. We demonstrate the existence of topological phase transitions by calculating all bulk Chern numbers and analyzing their corresponding topological edge states. By using current available techniques, we propose to measure bulk Chern numbers via Thouless pumping of light in modulated one-dimensional photonic waveguide arrays.