CSE chief executive Surekha Sellahewa said the rules for registering dealers will be submitted the board of the exchange on August 29.
Unlike a broker that acts for a client, a dealer can buy and sell on its account and make a market for a security.
Chairman of Sri Lanka's Securities and Exchange Commission Nalaka Godahwa said debt listings had started to increase following a tax break but there was very little secondary market trading.
Allowing primary dealers in Treasuries to act as market makers will boost the secondary market, he said.
Primary dealers who already have a capital of 300 million rupees under central bank rules will be allowed to deal corporate debt up to 5 percent of assets. They can also be an intermediary and work as a broker.
Existing stock brokers will also be allowed to be a debt dealers within their minimum capital requirements.
Sellahewa said other financial institutions could also apply to be dealers, but they needed a 100 million rupee capital.