BERLIN—Trade between Germany and China reached an all-time record last year. But when Chancellor Angela Merkel visits the country this week, she will carry a growing list of concerns from a wary business delegation.

The two export giants long had a symbiotic economic relationship. German companies are Europe’s largest investors in China and the fast-growing country has lapped up the capital goods—robots, machine tools, factory equipment—German businesses are experts at making.

This made China Germany’s biggest trading partner last year for the second time in a row, with trade between the two rising 10% to 186.7 billion EUROs ($219 billion). Unlike the U.S., Germany recorded only a modest trade deficit with China last year at 14.4 billion EUROs .

Yet the familiar grumbling of German business people about the difficulties of doing business in China is now becoming deafening. As Beijing erects new barriers shielding its market from foreigners, Germans are beginning to question their prospects there.

“There is a trend that worries German companies and we will address this,” said a Berlin government official this week.

In talks with President Xi Jinping and Premier Li Keqiang in Beijing on Thursday, Ms. Merkel will address compulsory joint ventures, requirements that companies share technical know-how and the inadequate legal protection of intellectual property, the official said.

One concern is China’s recent cybersecurity law that requires security reviews of technology products supplied to the Chinese government and critical industries.

China also tightened its control of virtual private networks used by companies to bypass China’s internet restrictions and protect their communications. Earlier this year, Beijing imposed rules that only allows VPNs approved by the Chinese government.