I completed diploma in ECE, after which I completed the three years b.tech program Can I pursue MS in USA?

Dear Suresh, if your bachelors degree says that it's a Btech - a 4 years US comparable degree, you may certainly apply to USA with GRE & TOEFL scores. The Ms in USA would be 1.5 to 2yrs & you may apply for the same one year prior to the intake you wish to go for. The intakes are majorly in Fall ie.