I have seen many companies TAX RATEs, but if it is Negative, what it means?
can anybody explain about this.

The rate itself cannot be negative. Rates are percentages. If you had a 35% rate, that rate is a positive number. So I don't see how you could be seeing negatives RATES.

However, you could see a negative tax AMOUNT. i.e. the tax itself, not the rate. This happens when you split the net income into different sections, and one of those sections is a negative number. If a number that is reflected in net income is negative, it will create a tax benefit, which is negative.

For instance, if your income from operations is 100,000 but you have an extraordinary loss of 10,000, that gives you a net income of 90,000. If you wanted to show the tax for each of those items separately, the 10,000 loss is reducing the net income down to 90,000 and therefore creates less tax.

100,000....... 35,000 tax operating income
(10,000)....... (3500) tax (loss)
90,000.......... 31,500 tax bottom-line net income

The actual tax would be 31,500. But the other amounts are shown on the statement, as applied to different areas of the income statement. If one of those areas is negative, the tax will also be negative. But the bottom-line tax will never be negative. If they have a net loss, they may be able to carry that loss to future years, but the IRS isn't going to give them money cause they had a loss; hence, no actual negative tax. Only negative amounts contributing to that bottom-line number.