The commission has come up with 190 new slogans judged more tasteful, such as "The mother earth is too tired to sustain more children".
The report on Sunday said: "Many slogans promoting the family planning policy are poorly worded, or full of strong language that leave an impression of simply forcing people to give up having more babies, causing misunderstanding on the policy and even tarnishing the image of the government.
"If such low-quality slogans, which may cause public complaint and resentment, are not corrected and remain where they are, the country's family planning efforts in the new era will be hindered."
Crude or insensitive slogans advocating family planning have been banned in China. Some examples:
- "Raise fewer babies but more piggies"
- "One more baby means one more tomb"
- "Houses toppled, cows confiscated, if abortion demand rejected"
Instead, they are to be replaced with 190 "tasteful" slogans, including:
- "Mother earth is too tired to sustain more children"
- "Both boys and girls are parents' hearts"
Source: Xinhua news agency
China's family planning policy limits most urban couples to just one child and allows some families in the countryside to have a second child if their first is a girl.
The government contends that the one-child policy has helped prevent at least 300 million births - about the size of the US population - and aided China's recent, rapid economic development.
Critics say it has led to forced abortions, sterilisations and a dangerously imbalanced sex ratio by bolstering a traditional bias for male offspring - seen as the mainstay for elderly parents.
Ruthless enforcement has triggered widespread opposition, especially in the countryside where children are valued as additional economic muscle.
Riots have broken out against forced abortions and other measures, such as heavy fines, the destruction of homes and confiscation of property.
However, ruling Communist Party officials and the rich often ignore the law themselves or pay the necessary fines.
China already has the world's largest population, at 1.3 billion people.