“价格战”常见的英文表达是 price war。
例句：
The two companies have been engaged in a fierce price war to gain more market share.（这两家公司为了获取更多市场份额，一直在进行激烈的价格战。）
A price war broke out in the smartphone market last year.（去年智能手机市场爆发了一场价格战 。）