There are many challenges in testing of Graphical User Interface (GUI) applications due to its event driven nature and infinite input domain. Testing each and every possible combination of input require creating number of test cases to satisfy the adequacy criteria of GUI testing. It is not possible to test each and every test case within specified time frame. Therefore it is important to assign higher priority to test cases which have higher fault revealing capability than other test cases. Various methods are specified in literature for test suite prioritization of GUI based software and some of them are based on interaction coverage and weight of events. Weight based methods are defined namely fault prone weight based method, random weight based method and equal weight based method in which fault prone based method is most effective. In this paper we have proposed Event-Coverage and Weight based Method (EC-WBM) which prioritizes GUI test cases according to their event coverage and weight value. Weight value will be assigned based on unique event coverage and fault revealing capability of events. Event coverage based method is used to evaluate the adequacy of test cases. EC-WBM is evaluated for 2 applications one is Notepad and another is Calculator. Fault seeding method is used to create number of versions of application and these faults are evaluated using APFD (Average percentage of fault detection). APFD for prioritized test cases of Notepad is 98% and APFD for non-prioritized test cases is 62%.