This is illegal because it violates the privacy of others. Personal privacy is protected by law. Invading others' private lives and revealing others' privacy is both a violation of social morality and an illegal act. Surveillance, spying on other people's private lives, spying on other people's secrets by reading diaries and opening letters privately are all acts of violating privacy.

Legal basis:

People's Republic of China (PRC) Civil Code

Article 1032 Natural persons have the right to privacy. No organization or individual may infringe upon the privacy rights of others by spying, harassing, exposing or making public.

Privacy is the private space, private activities and private information that natural people live in peace and don't want to be known by others.

Article 103 Unless otherwise provided by law or expressly agreed by the obligee, no organization or individual may commit the following acts:

(a) by telephone, SMS, instant messaging tools, e-mail, leaflets, etc. Disturb the private life of others;

(2) Entering, taking photos or peeping into other people's private spaces such as houses and hotel rooms;

(3) Shooting, peeping, eavesdropping or revealing other people's private activities;

(4) Shooting or peeping at the private parts of others' bodies;

(5) handling other people's private information;

(6) Infringe upon the privacy of others in other ways.