1).Uncomment the following line in the project.properties file
proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-project.txt
2).Inside AndroidSDk/tools/proguard/proguard-project.txt Add bellow lines ,Because our project uses WebView with JS So,we have to specify the fully qualified class name to the JavaScript interface class:
-keep public class * extends org.apache.cordova.CordovaPlugin
-keep public class * extends com.phonegap.api.Plugin
-keep class org.apache.cordova.** { *; }
-dontwarn android.webkit.*
3).Build Android project.
4).Copy “proguard-project.txt “ file from “AndroidSDk/tools/proguard/proguard-project.txt” to android folder.
5).Export signed package :Right click on project > android tools > Export signed application package