The invention discloses a metal drag reducer for coiled tubing. Water serves as a dispersion medium, other components comprise, by weight, 82%-90% of basic mineral oil, 4%-10% of oil-soluble emulsifier, 1%-2% of temperature stabilizer, 2%-5% of metal corrosion inhibitor and 0.1%-1% of defoamer. The oil-soluble emulsifier is nonionic surfactant Span20, and the HLB value of the oil-soluble emulsifier is 8.6. The temperature stabilizer is sulfomethal phenolaldehy resin. The metal corrosion inhibitor is octadecylamine corrosion inhibitor. Or 5 wt%-15 wt% of sodium dodecyl benzene sulfonate is added and compounded for use. The defoamer is modified organopolysiloxane defoamer or waste machine oil, or the modified organopolysiloxane defoamer and the waste machine oil are compounded for use. The friction resistance coefficient between metal tubular columns can be greatly reduced through a low-concentration water solution of a system, the self-locking degree of the coiled tubing is reduced, and the extension length of the coiled tubing on the horizontal section is increased.