I’ve noticed that many people don’t have a deep enough understanding of the KDJ indicator, especially regarding the parameter settings. Today I want to share some of my trading insights accumulated over the years.

First, it’s important to understand the essence of KDJ. This indicator studies the relationship between the highest price, lowest price, and closing price, combining momentum concepts and moving averages’ advantages, so it can quickly and intuitively assess market trends. It is most widely used in stock and futures markets, especially for short- to medium-term trend analysis.

Talking about the three lines, the J line fluctuates the most frequently, the K line is next, and the D line is the most stable. In terms of sensitivity, the J value is the most reactive but also the easiest to generate false signals, the K value is in the middle, and the D value is the slowest but most reliable. That’s why many people say signals from the J line are the most trustworthy, because they appear less often but with higher accuracy.

Both the K and D values range from 0 to 100, but the J value can exceed 100 or drop below 0. In practical application, when the D value is above 80, it indicates overbought; below 0 indicates oversold. When the J value exceeds 100 or drops below 0, extra caution is needed. I personally often look for the K line crossing above the D line to buy, and crossing below to sell.

Regarding the KDJ parameter settings, this is an area many people tend to overlook. The system default is 9, but in actual trading, using this parameter on daily K-lines can be too sensitive, resulting in too many false signals. Based on my experience, I usually change the parameters to one of 5, 19, or 25, which works much better. The specific choice depends on different stocks and timeframes, and should be adjusted flexibly.

There are a few key points when applying it. In a bullish market where the price is above the 60-week moving average, a buy signal occurs when the weekly J line is below zero, then turns upward and closes with a positive candle. Conversely, in a bearish market, the J line often flattens below zero; don’t rush to buy—wait until it truly turns upward. The same applies to selling: when the J line reaches above 100 and turns downward with a bearish candle, be alert for a top.

However, KDJ also has obvious flaws. During a strong uptrend or downtrend, the indicator can become dull, increasing false signals. When the K value enters overbought or oversold zones, it often hovers, making traders feel helpless. When short-term price fluctuations are too intense, using KD crossovers to buy or sell often results in buying at the high and selling at the low.

That’s why parameter setting for KDJ is so critical. I’ve seen many veteran investors specifically look for J line signals to grasp the best entry and exit points because J signals appear less frequently and are particularly reliable once they do. Especially when the J value stays above 100 or below 0 for three consecutive days, a short-term top or bottom is often imminent.

Another very important point is that KDJ is suitable for use in ranging markets. Once a strong trending market begins, you need to change your approach. The weekly KDJ provides better guidance for medium-term operations. In summary, to use this indicator effectively, the parameter settings must be reasonable, and it should be combined with the market’s nature for flexible application to truly unleash its power.