Code 7 (Normal Distribution) is not taxable if retired after meeting the plan retirement age and/or years of service. For a Code D, see annuities below. Code 8 (Excess Contributions) is taxable to the extent there are excess earnings, or the employer did not include the contributions as taxable compensation.

The distribution is not subject to penalty but the amount shown in box 2a is subject to ordinary income tax at your marginal tax rate. 

Click this link for more info on Code 8 in 1099-R . 

Thanks for the replay but my real question is when I got 1099-R it paid tax to PA again but the source of contribution already paid tax to PA before it contributed into my 401k account. So can I get refund from PA when I file tax? If not I paid tax two times for the same money. 

When you earned the 401k income, it was taxed by PA and not federal, supposedly. Your code 8 says something went amiss and you do have taxable income. You said there is also state tax withheld. Taxable income and state tax make sense together for this new amount. The fact that you don't recognize having something odd makes me wonder. Did you have an excess amount of 401K withheld? Did the company do something?  I recommend you contact your employer and find out why you have the code 8. Is this the correct information or do you need a corrected form?