The organisation was created by China, Russia and four Central Asian countries in 2001 as a countermeasure to limit the influence of Western alliances such as Nato.
This year’s gathering is the largest since the organisation was founded.
For Tianjin, the summit has become a major event with banners and billboards promoting it throughout the northern port city.
At night tens of thousands of local spectators have been cramming into the riverside area to see a lightshow displayed on tower blocks while the gathering is taking place.
The streets have been heavily crowded – making it difficult for people to even move, especially on and around the historic Jiefang Bridge.
During the day pedestrians are at times being made to wait as roadblocks go up to allow the motorcades of visiting world leaders to pass by quickly.
Taxis and other hire car services have been suspended in the downtown area, but this has not dampened the enthusiasm of crowds of people wanting to be part of what has been described as a historic meeting.
However, police have advised Tianjin’s more than 13 million residents to avoid moving around the city if possible and to stick to shops nearby them to purchase any immediate necessities.
The meeting comes days before the massive military parade that will mark 80 years since the end of World War II.