Moya Greene's pay package for the year to the end of March will be revealed in the company's annual report in the next few weeks and make her the UK's best-paid public sector boss, the Sunday Times reported.
Ms Greene's pay of £1.1 million in the year to the end of March 2012 included a salary of £498,000, bonus of £371,000, £200,000 in lieu of pension and benefits of £38,000.
A long-term bonus plan could see Ms Greene also earn an extra £488,000 for the year to end of March 2013.
The award, due to vest in March 2014, is based on performance targets for the previous three years. It would take her total pay to almost £1.6 million.
The payout would still lag behind a £2.4 million package earned by her predecessor Adam Crozier, and comes amid improving performance at the letter and parcel delivery firm.
When Ms Greene joined in July 2010 Royal Mail had negative cash flow of £210 million, but this had improved to positive cash flow of £334 million in its latest results.
The Government's plans to float the Royal Mail on the stock market later this year, but workers massively rejected the plan in a recent vote. A ballot of 112,000 delivery, sorting office and other postal staff by the Communication Workers Union (CWU) showed that 96% opposed the planned sell-off.
A Royal Mail spokeswoman said: "Executive remuneration will be disclosed in the usual way in our annual report and accounts. Awards are only made following the delivery of stretching and sustainable performance."