No deaths were reported in Pingyuan on Sunday.
Pingyuan is about 345km south of Beijing.
Shandong TV reported that 126 houses had collapsed as of 7am.
All of the injured were being treated at Pingyuan County First People’s Hospital.
The tremors were reported in several areas in northern China, including Beijing and Tianjin and the provinces of Henan and Hebei.
The quake shook furniture in homes and sent residents seeking refuge outside, according to videos posted online.
“In the middle of the night, there was a sudden boom outside, and the ground began to shake, so I hurriedly got dressed and rushed out,” a Pingyuan resident posted on social media.
“Can I sleep now?” other commenters posted below the earthquake centre’s notice on the quake.
Quake-related searches dominated the hot search list on Weibo on Sunday morning.
Liu Xiqiang, deputy director of the Shandong Earthquake Agency, said it was the first time that an earthquake of magnitude 5 or higher had struck within 50km of the county.
Liu added that the possibility of a bigger aftershock was low.
Authorities in Pingyuan said they temporarily cut gas supplies in the county in case the quake had damaged pipelines.
Dozens of services on the Beijing-Shanghai high-speed rail line – the nation’s busiest – which passes through the quake zone, have been delayed or suspended, according to China Railway Beijing Group.
Authorities in Shandong province launched an emergency response and set up a joint command with the local government to take charge of disaster relief.
The State Council’s earthquake relief headquarters and the Ministry of Emergency Management also sent teams to work at the quake site.
The Beijing Earthquake Agency said the quake in Shandong would not affect Beijing in the short term.
Fan Xiao, a geologist based in the southwestern province of Sichuan, said the collapse of more than 100 houses could reveal problems with the quality of construction.
“If they collapsed in a magnitude 5.5 quake, it means the seismic design of the buildings is not up to standard,” Fan said.
He said Pingyuan county, located in northwestern Shandong, was geologically part of the North China Plain and “not the most seismically active or destructive place in Shandong’s history”.
Fan added that Shandong’s biggest danger, and the one that the geology department should monitor, was the Tan-Lu fault across the eastern part of the province.
The area was the site of the Great Tancheng Earthquake in 1668, which was estimated to be of magnitude 8.5 and thought to be the biggest ever recorded in eastern China.
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