The spacecraft was successfully docked by European astronaut Tim Peake using the orbiting lab's robotic arm, with help from US astronaut Jeff Williams.
Carrying nearly 3,175 kg of cargo including an expandable habitat known as the Bigelow Expandable Activity Module (BEAM), crucial for future deep space exploration, SpaceX's Dragon cargo ship arrived at the International Space Station (ISS) on Sunday.
The spacecraft was successfully docked by European astronaut Tim Peake using the orbiting lab's robotic arm, with help from US astronaut Jeff Williams, Xinhua quoted the US space agency NASA as saying.
Another US commercial cargo ship called Cygnus has been attached to the station since March 26. Two Russian Soyuz crew capsules and two Progress cargo ships are also docked at the moment. As a result, "Dragon' s arrival marks the first time two commercial cargo vehicles have been docked simultaneously at the space station," NASA said.
"With the arrival of Dragon, the space station ties the record for most vehicles on station at one time -- six," said NASA.
The last time six vehicles were docked to the station was back in the space shuttle era, when Discovery visited in February 2011.
The 1,400 kg BEAM is a $17.8 million project that will test the use of an inflatable space habitat in micro-gravity.
BEAM is expected to be filled with air to expand four and a half times its original volume at the end of May after being attached to the ISS.
During its two-year test mission, astronauts will enter the module for a few hours several times a year to retrieve sensor data and assess conditions.
Inflatable habitats are designed to take up less room on a rocket, but provide greater volume for living and working in space once expanded, NASA said, noting that this test allows investigators to gauge how well the expandable habitat protects itself against solar radiation, space debris and contamination.
Science experiments on-board Dragon included those that will help investigators study muscle atrophy and bone loss in space, seek insight into the interactions of particle flows at the nano scale level and use protein crystal growth in micro-gravity to help design new drugs.
The spacecraft was launched on Friday from Cape Canaveral, Florida, atop the California-based company's own Falcon 9 rocket, which made history by landing the first stage of its Falcon 9 rocket on a droneship in the Atlantic Ocean for the first time.
Dragon will remain connected to the ISS until May 11, when it will depart for a parachute-assisted splashdown off the coast of California, bringing almost 3,500 pounds (1,600 kilograms) of science, hardware and spacewalking tools back to Earth for further study.