The two banks are also working on procedures to ensure that loans include safeguards in labour, environmental and anti-corruption rules, ADB president Takehiko Nakao told the Financial Times in an interview.
People have been keen to depict the two banks and their presidents as rivals, "but actually we are friends, and ADB and AIIB can be partners", Nakao told the Financial Times.
"We’re already identifying projects for the first batch of AIIB loans. One of them should be co-financing between AIIB and ADB," he said.
Nakao has discussed the need for social and environmental safeguards with AIIB president Jin Liqun and the ADB will support the AIIB in developing policies and guidelines, the Financial Times said.
The AIIB was announced in Beijing in 2014, with the aim of boosting investment in infrastructure in Asia and was established formally by the 57 member countries signing the Articles of Agreement in June 2015.
Work with the ADB has been "on the cards for a while now", said Beijing-based infrastructure expert Greg Jones of Pinsent Masons, the law firm behind Out-Law.com.
"This has been under discussion since the foundation of the AIIB. It's a sensible move for the AIIB as it boosts the credibility of its early loans if they're co-financed with the ADB, and it gives its staff the opportunity to get up to speed with the ins and outs of development finance," he said
"The ADB will probably hope to persuade the AIIB to adopt much of its lending criteria, which are increasingly focused on social inclusion and environmental sustainability rather than pure GDP growth. However, this won't necessarily be the case as AIIB has made it clear it wants to differentiate itself by being more agile than existing institutions," Jones said.
"I also suspect the AIIB will have a greater focus on economic infrastructure such as power and transport, whereas the ADB's focus is more on social infrastructure like schools and healthcare," he said.
"The AIIB will pick and choose the lending criteria it feels fit its own goals rather than take a wholesale adoption route. It aims to be different and while a co-financing may result in some alignment with the ADB the differences will remain," Jones said.
Japanese prime minister Shinzo Abe said in November 2015 that Japan would aim to halve the time it takes to get a development loan, to compete with the AIIB.
Japan, along with the US, chose not to follow countries including the UK, France and Australian in joining the AIIB.
The country will cut the time it takes to get a loan from three years to between 18 months and two years, and end its practice of requiring government guarantees for each loan, Abe said, and Japan will aim to provide US$110 billion of infrastructure funding in Asia over the next five years.