Ray-tracing (RT) technology has received much attention with the fast advances of the fifth-generation (5G) mobile communication. Based on our self-developed ray-tracing platform CloudRT and 3D electronic map, 5G band (3.5-3.6 GHz) wireless channels are simulated in dense urban areas and the second-order channel characteristics including delay spread (DS), azimuth angle spread of arrival (ASA), elevation angle spread of arrival (ESA) and multi-path power ratio are visualized and analyzed. This is of great significance for analyzing the channel characteristics in the 5G frequency band, for better signal coverage and other engineering demands. This study is concluded by drawing several statistical conclusions and pointing out future research directions.