The words 常常 and 往往 can both be translated as ‘often’, but their usage isn’t quite the same. It doesn’t take too long to straighten the differences out, and it’s worth doing as little improvements like this all add up to sounding more native.
Here’s a quick guide to the situations in which 常常 and 往往 should be used.
常常 is a general-purpose word for ‘often’ or ‘frequently’. The meaning isn’t much more complicated than that. Pretty much any situation that can be described with ‘often’ in English can be described with 常常 in Mandarin.
常常 can be used for past, present, future or conditional events. It can also be used for hypothetical events or ideas.
Note that the negative of 常常 is usually just 不常. You don’t often hear *不常常.
我常常看书。 Wǒ chángcháng kàn shū. “I often read books.”
我弟弟小的时候，我常常陪他去公园。 Wǒ dìdi xiǎo de shíhou , wǒ chángcháng péi tā qù gōngyuán. “When my brother was young, I often used to take him to the park.”
要是我有钱的话，我将常常出去玩儿。 Yàoshi wǒ yǒu qián dehuà , wǒ jiāng chángcháng chūqù wánr. “If I had the money, I would often go out and have fun.”
我一有小狗，就会开始常常散步。 Wǒ yī yǒu xiǎogǒu , jiù huì kāishǐ chángcháng sànbù. “As soon as I have a dog, I’ll start going for walks frequently.”
因为她是个很实际的人，她常常把朋友得气车修好。 Yīnwèi tā shì ge hěn shíjì de rén , tā chángcháng bǎ péngyou děi qìchē xiū hǎo. “As she’s a very practical person, she often fixes her friends’ cars.”
However, this last sentence could use 往往. It’s not incorrect with 常常, but 往往 is probably better, because…
往往 is also used to indicate frequency, but must appear with a reason or condition that causes the event to occur frequently. It can’t just appear in a simple statement that something often happens. 往往 can be used for present events, but is most commonly used for past events. It cannot be used for future, conditional or hypothetical events.
他不太能喝酒，但是朋友都喜欢喝，所以他往往喝醉了。 Tā bù tài néng hē jiǔ , dànshì péngyou dōu xǐhuān hē , suǒyǐ tā wǎngwǎng hēzuì le. “He’s not a big drinker, but his friends all like to drink, so he often gets drunk.”
因为体育场离我家不远，我往往去看足球赛。 Yīnwèi tǐyùchǎng lí wǒ jiā bù yuǎn , wǒ wǎngwǎng qù kàn zúqiúsài. “As the stadium isn’t far from my house, I often go and watch football matches.”
小李往往失眠是因为他的邻居老是嘈杂地吵架。 Xiǎo lǐ wǎngwǎng shīmián shì yīnwèi tā de línjū lǎoshi cáozá dì chǎojià. “Xiaoli often loses sleep because his neighbours are always arguing loudly.”
Note that a sentence with 往往 doesn’t necessarily need 因为 or 所以:
这家饭馆下午的时候往往没有很多顾客。 Zhè jiā fànguǎn xiàwǔ de shíhou wǎngwǎng méiyǒu hěn duō gùkè. In the afternoon, this restaurant doesn’t often have a lot of customers.
It just needs to include a reason for the frequency of the event.