Hong Kong Mass Transit Railway (MTR) is one of the most profitable urban rail transit systems in the world, providing a convenient way to access most corners of the city. Nevertheless, network vulnerability has drawn public attention due to the frequent disruptions. This paper aims to evaluate the route redundancy of Hong Kong metro network, which has been suggested in system analysis as a good characteristic to combat vulnerability. To carry out this analysis, definitions of alternative routes and a solution algorithm are described to calculate the travel alternative diversity and the top ten vulnerable stations are identified. In addition, the same approach is adopted to study the impact of a new metro line, the Shatin to Central Link (SCL), to be completed in 2021. Overall, this study aims to provide significant insights that can help understand the topology of Hong Kong Metro network for the pre-disaster transportation system evaluation and planning.