Yes, but not flash charge, super flash charge, only ordinary charging, slower than the original charger. In addition to the charging speed, it may cause damage to the battery, so it is recommended to use the original charger to charge. Mobile phone charger charging voltage, current is generally 5V-1A (or 1--4A), if other brand charger parameters in line with 5V, 1-2A, is rechargeable, lithium-ion battery is best to choose a special charger, otherwise it may not reach saturation state, affecting its performance, but for the sake of mobile phone safety and normal use, it is recommended to use the standard charger.
OPPO fast charging can be used with Xiaomi, because the fast charging head is suitable, any fast charging head can be used on all mobile phones, and the charging power is the same, and the time is about the same.