The invention provides a fitness bike trainer control system realizing stepless control by an Android/IOS mobile terminal APP. The fitness bike trainer control system comprises a display module, an Android/IOS mobile terminal APP master control module, a live-action video module, an information storage module, a Bluetooth module, a fitness trainer master control module, a resistance module and a sensor module. A user uses the Android/IOS mobile terminal APP in a mobile phone to steplessly control the fitness bike trainer; the fitness trainer receives resistance gear information from the Android/IOS mobile terminal APP, PWM output current percentage of the fitness trainer is controlled through combination with a PID fuzzy control algorithm so as to control the magnetic field of an electromagnet of the fitness trainer, the magnetic field of the electromagnet and the magnetic field of a permanent magnet jointly brake an aluminum plate, user riding resistance is generated, and a riding speed is fed back to the Android/IOS mobile terminal APP. The Android/IOS mobile terminal APP can set and store identities and motion information of multiple users, can perform training effect comparison, can display real-time data information about user riding and has a live-action video training function, thereby being capable of meeting fitness requirements of different users.