Citizen Lab said it had investigated filters set up for customers who wanted something engraved on a new iPhone, iPad or other Apple device.
And Apple had a broad list of censored words, not just in mainland China but also in Hong Kong and Taiwan.
Apple said its systems "ensure local laws and customs are respected".
"As with everything at Apple, the process for engraving is led by our values," chief privacy officer Jane Horvath wrote in a letter provided to CitizenLab in advance of the publication of its report.
