Technology drive today many things has been replaced with better design and technique. The research throughout designing and constructing of Capacitive Discharge Ignition CDI system for Spark Ignition SI Engine which is based on electronic ignition and contact point ignition. CDI system is composed of pulse generation circuit, pulse control circuit, main charge and discharge capacitor coil and spark plug. Mainly composed of pulse control circuit and pulse generation circuit which main function is to generate DC high voltage when the DC 12V supply from car battery. Pulse control circuit generates the pulse to control oscillator on and off state and trigger gate drive pulse to the SCR. When the SCR from pulse control circuit open, the main capacitor discharge high voltage 300V from pulse generation to ignition coil. The coil generates high voltage 25 30kV which it depends on number of turn ration from coil primary and secondary winding. System is divided into ten blocks. The operation and function of each block is mentioned in detail. Design calculations for inverter, rectifier and selection of SCR, analyzing of components are highlighted for system. Su Su Yi Mon "Capacitive Discharge Ignition (CDI) System for Spark Ignition (SI) Engine (Pulse Control Circuit)" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26773.pdf