The conjunction 否则 and the structure 除非…，否则…
The conjunction 否则
否则 
is an alternative conjunction. It indicates that if a certain condition is not met, there will be undesirable consequences.
is an alternative conjunction. It indicates that if a certain condition is not met, there will be undesirable consequences. Pay attention
The alternative conjunctions (转折连接词) are function words that express contrast and differentiation.
Scheme
condition
,
否则
undesirable consequences
The recommendation is usually described in the first part of a sentence. In some cases, it has the meaning "it's a good thing that...".
Possible negative consequences are described in the second part of a sentence. In other words, the second part of a sentence states what can happen if a certain condition is not met.
Examples
谢谢你通知我，否则我不知道这件事了
Thank you for notifying me. Otherwise I wouldn't have known about it
xièxie nǐ tōngzhī wǒ, fǒuzé wǒ bù zhīdào zhè jiàn shì le
我们不要告诉任何一个人，否则我们就完蛋了
We shouldn't tell anyone, otherwise we're screwed
wǒmen bú yào gàosu rènhé yí ge rén, fǒuzé wǒmen jiù wándàn le
他必须进行手术，否则他会死的
He needs surgery or he will die
tā bìxū jìnxíng shǒushù, fǒuzé tā huì sǐ de
The structure 除非…，否则…
否则 is often used with 除非 :
:Scheme
除非
A
否则
B
It indicates that the result "B" will occur under any other conditions except for condition "A".
It is translated as "unless..., ...".
Examples
除非下雪，否则我一定开车过来
I'll come unless it snows
chúfēi xià xuě, fǒuzé wǒ yídìng kāichē guòlái
Here, the result "B" is “I will come”. It will happen unless condition "A" exists, that is, if it snows.
Examples
除非能对人们造成影响，否则这种的项目意义不大
This kind of project makes little sense if it doesn't have an impact on people
chúfēi néng duì rénmen zàochéng yǐngxiǎng, fǒuzé zhè zhǒng de xiàngmù yìyì bú dà
Here, the result "B" is "this project makes little sense" unless condition "A" exists, that is, if it doesn't have an impact on people.