Afghanistan scored 21, Bangladesh 48, Nepal 45 and Pakistan 38. Among the 'A' grade countries were South Africa, New Zealand, UK, France, Sweden and the US.
"In relative terms we are doing well, the region is also doing well one way or another," Pakiasothy Saravanamuttu from Centre for Policy Alternatives, OBI's local partner said.
"The challenge, however is to do much better."
OBI said Sri Lanka gave enough information for citizens to assess "how the government manages public funds."
Sri Lanka has an executive budget proposal, a pre-budget statement, an enacted budget and mid-year reports, and an audit report, OBI said.
From 2006 to 2008 budget transparency has increased, the report said, with more comprehensive reports with extra information coming out.
But OBI said the state said Sri Lanka's state auditor did not have enough resources to "meaningfully exercise its mandate" and it should be given more resources.
Others, including the Sri Lanka chapter of Transparency International and lawmakers have also raised questions about the budgets before 2009 in particular which were so way off target so as to mislead the entire parliament and the nation.
After 2009 the International Monetary Fund started monitoring fiscal activities after they bailed out Sri Lanka leading to budgets projects which were less fanciful.