解决方法

方法1：将X轴的样式设置为value（默认），不要设置为time（见示例代码）
方法2：设置x轴的最大及最小值

示例代码

import pyecharts.options as opts
from pyecharts.charts import Line
import pandas as pd
import numpy as np


def plot_cumulative_returns(dataframe: pd.DataFrame):
    """绘图：曲线图
    :param dataframe: 绘图用的dataframe, 每一行是一个时间点，每一列是一组数据
    """
    line_plot = Line(init_opts=opts.InitOpts(width="1400px", height="800px"))
    line_plot.add_xaxis(xaxis_data=dataframe.index.strftime("%Y-%m-%d").values.tolist())
    for col_name, col_series in dataframe.iteritems():
        line_plot.add_yaxis(
            series_name=col_name,
            y_axis=col_series,
            linestyle_opts=opts.LineStyleOpts(width=2, type_='solid'),
            label_opts=opts.LabelOpts(is_show=False),  # 不显示坐标值
        )

    # 设置全局样式
    line_plot.set_global_opts(
        xaxis_opts=opts.AxisOpts(name="时间", ),  # 设置横坐标代表的含义
        datazoom_opts=opts.DataZoomOpts(
            is_show=True,
            range_start=50,
        ),
    )

    line_plot.render("my_plot.html")


def main():
    data = np.random.random(size=(200, 2))
    data = np.cumsum(data, axis=0)
    plot_df = pd.DataFrame(data,
                           index=pd.date_range(start="20200101", periods=200, freq="D"),
                           columns=["line1", "line2"])
    plot_cumulative_returns(plot_df)


if __name__ == '__main__':
    main()