Many software development projects were not able to meet their deadlines with expected qualities under budgets. Basically, it was because the stakeholders and the de-velopment team sharing different expectations and misunderstanding the essence of how software was built. In most cases, the budget and resources were allocated according to the Functional Requirements, which described the features about the software. But on the contrary the development teams were striving in making decision about how to mitigate those Non-functional Requirements which were not included in the budget during the development cycle. However, to mitigate the Non-functional Requirements is not without a price, and letting development team impose resources arbitrarily will make software budget estimation more complicated and worse. This research pointed out what Non-functional Requirements should be abides by the international standard ISO 9126, offered a relatively accurate budget estimation framework. The framework showed how the stakeholders and the development team reach the consensus about the software, how to integrate with Cost Accounting to monitor the budget distribution and to implicate how software should be scheduled and estimated the cost for next coming projects.