Due to the variety of sensors and portability of mobile phones, an increasing amount of mobile apps are released for the purpose of health monitoring. To design a new health monitoring app, a conventional approach is to define a goal model with the intervention of stakeholders. As there are a large number of apps in this domain, many of them have similar features, which can be exploited to reduce the time consumption of requirements elicitation, improve their quality and help the requirements prioritization. In this paper, we propose a novel requirements engineering approach by analysing similar apps. In this approach, we identify similar apps and analyze their descriptions, user reviews, Android APK and source code for the construction and enrichment of a Domain Feature Model. This model will be used as a support for the requirements engineers in different phases of requirements engineering.